StringUtils 方法
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/*
* Copyright 2002-2005 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.lang;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* <p>Operations on {@link java.lang.String} that are
* <code>null</code> safe.</p>
*
* <ul>
* <li><b>IsEmpty/IsBlank</b>
* - checks if a String contains text</li>
* <li><b>Trim/Strip</b>
* - removes leading and trailing whitespace</li>
* <li><b>Equals</b>
* - compares two strings null-safe</li>
* <li><b>IndexOf/LastIndexOf/Contains</b>
* - null-safe index-of checks
* <li><b>IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut</b>
* - index-of any of a set of Strings</li>
* <li><b>ContainsOnly/ContainsNone</b>
* - does String contains only/none of these characters</li>
* <li><b>Substring/Left/Right/Mid</b>
* - null-safe substring extractions</li>
* <li><b>SubstringBefore/SubstringAfter/SubstringBetween</b>
* - substring extraction relative to other strings</li>
* <li><b>Split/Join</b>
* - splits a String into an array of substrings and vice versa</li>
* <li><b>Remove/Delete</b>
* - removes part of a String</li>
* <li><b>Replace/Overlay</b>
* - Searches a String and replaces one String with another</li>
* <li><b>Chomp/Chop</b>
* - removes the last part of a String</li>
* <li><b>LeftPad/RightPad/Center/Repeat</b>
* - pads a String</li>
* <li><b>UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize</b>
* - changes the case of a String</li>
* <li><b>CountMatches</b>
* - counts the number of occurrences of one String in another</li>
* <li><b>IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable</b>
* - checks the characters in a String</li>
* <li><b>DefaultString</b>
* - protects against a null input String</li>
* <li><b>Reverse/ReverseDelimited</b>
* - reverses a String</li>
* <li><b>Abbreviate</b>
* - abbreviates a string using ellipsis</li>
* <li><b>Difference</b>
* - compares two Strings and reports on their differences</li>
* <li><b>LevensteinDistance</b>
* - the number of changes needed to change one String into another</li>
* </ul>
*
* <p>The <code>StringUtils</code> class defines certain words related to
* String handling.</p>
*
* <ul>
* <li>null - <code>null</code></li>
* <li>empty - a zero-length string (<code>""</code>)</li>
* <li>space - the space character (<code>' '</code>, char 32)</li>
* <li>whitespace - the characters defined by {@link Character#isWhitespace(char)}</li>
* <li>trim - the characters <= 32 as in {@link String#trim()}</li>
* </ul>
*
* <p><code>StringUtils</code> handles <code>null</code> input Strings quietly.
* That is to say that a <code>null</code> input will return <code>null</code>.
* Where a <code>boolean</code> or <code>int</code> is being returned
* details vary by method.</p>
*
* <p>A side effect of the <code>null</code> handling is that a
* <code>NullPointerException</code> should be considered a bug in
* <code>StringUtils</code> (except for deprecated methods).</p>
*
* <p>Methods in this class give sample code to explain their operation.
* The symbol <code>*</code> is used to indicate any input including <code>null</code>.</p>
*
* @see java.lang.String
* @author <a href="http://jakarta.apache.org/turbine/">Apache Jakarta Turbine</a>
* @author GenerationJavaCore
* @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
* @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a>
* @author <a href="mailto:gcoladonato@yahoo.com">Greg Coladonato</a>
* @author <a href="mailto:bayard@generationjava.com">Henri Yandell</a>
* @author <a href="mailto:ed@apache.org">Ed Korthof</a>
* @author <a href="mailto:rand_mcneely@yahoo.com">Rand McNeely</a>
* @author Stephen Colebourne
* @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
* @author Holger Krauth
* @author <a href="mailto:alex@purpletech.com">Alexander Day Chaffee</a>
* @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
* @author Arun Mammen Thomas
* @author Gary Gregory
* @author Phil Steitz
* @author Al Chou
* @author Michael Davey
* @since 1.0
* @version $Id: StringUtils.java 161243 2005-04-14 04:30:28Z ggregory $
*/
public class StringUtils {
// Performance testing notes (JDK 1.4, Jul03, scolebourne)
// Whitespace:
// Character.isWhitespace() is faster than WHITESPACE.indexOf()
// where WHITESPACE is a string of all whitespace characters
//
// Character access:
// String.charAt(n) versus toCharArray(), then array[n]
// String.charAt(n) is about 15% worse for a 10K string
// They are about equal for a length 50 string
// String.charAt(n) is about 4 times better for a length 3 string
// String.charAt(n) is best bet overall
//
// Append:
// String.concat about twice as fast as StringBuffer.append
// (not sure who tested this)
/**
* The empty String <code>""</code>.
* @since 2.0
*/
public static final String EMPTY = "";
/**
* Represents a failed index search.
* @since 2.1
*/
public static final int INDEX_NOT_FOUND = -1;
/**
* <p>The maximum size to which the padding constant(s) can expand.</p>
*/
private static final int PAD_LIMIT = 8192;
/**
* <p>An array of <code>String</code>s used for padding.</p>
*
* <p>Used for efficient space padding. The length of each String expands as needed.</p>
*/
private static final String[] PADDING = new String[Character.MAX_VALUE];
static {
// space padding is most common, start with 64 chars
PADDING[32] = " ";
}
/**
* <p><code>StringUtils</code> instances should NOT be constructed in
* standard programming. Instead, the class should be used as
* <code>StringUtils.trim(" foo ");</code>.</p>
*
* <p>This constructor is public to permit tools that require a JavaBean
* instance to operate.</p>
*/
public StringUtils() {
// no init.
}
// Empty checks
//-----------------------------------------------------------------------
/**
* <p>Checks if a String is empty ("") or null.</p>
*
* <pre>
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
* </pre>
*
* <p>NOTE: This method changed in Lang version 2.0.
* It no longer trims the String.
* That functionality is available in isBlank().</p>
*
* @param str the String to check, may be null
* @return <code>true</code> if the String is empty or null
*/
public static boolean isEmpty(String str) {
return str == null || str.length() == 0;
}
/**
* <p>Checks if a String is not empty ("") and not null.</p>
*
* <pre>
* StringUtils.isNotEmpty(null) = false
* StringUtils.isNotEmpty("") = false
* StringUtils.isNotEmpty(" ") = true
* StringUtils.isNotEmpty("bob") = true
* StringUtils.isNotEmpty(" bob ") = true
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if the String is not empty and not null
*/
public static boolean isNotEmpty(String str) {
return str != null && str.length() > 0;
}
/**
* <p>Checks if a String is whitespace, empty ("") or null.</p>
*
* <pre>
* StringUtils.isBlank(null) = true
* StringUtils.isBlank("") = true
* StringUtils.isBlank(" ") = true
* StringUtils.isBlank("bob") = false
* StringUtils.isBlank(" bob ") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if the String is null, empty or whitespace
* @since 2.0
*/
public static boolean isBlank(String str) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return true;
}
for (int i = 0; i < strLen; i++) {
if ((Character.isWhitespace(str.charAt(i)) == false)) {
return false;
}
}
return true;
}
/**
* <p>Checks if a String is not empty (""), not null and not whitespace only.</p>
*
* <pre>
* StringUtils.isNotBlank(null) = false
* StringUtils.isNotBlank("") = false
* StringUtils.isNotBlank(" ") = false
* StringUtils.isNotBlank("bob") = true
* StringUtils.isNotBlank(" bob ") = true
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if the String is
* not empty and not null and not whitespace
* @since 2.0
*/
public static boolean isNotBlank(String str) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return false;
}
for (int i = 0; i < strLen; i++) {
if ((Character.isWhitespace(str.charAt(i)) == false)) {
return true;
}
}
return false;
}
// Trim
//-----------------------------------------------------------------------
/**
* <p>Removes control characters (char <= 32) from both
* ends of this String, handling <code>null</code> by returning
* an empty String ("").</p>
*
* <pre>
* StringUtils.clean(null) = ""
* StringUtils.clean("") = ""
* StringUtils.clean("abc") = "abc"
* StringUtils.clean(" abc ") = "abc"
* StringUtils.clean(" ") = ""
* </pre>
*
* @see java.lang.String#trim()
* @param str the String to clean, may be null
* @return the trimmed text, never <code>null</code>
* @deprecated Use the clearer named {@link #trimToEmpty(String)}.
* Method will be removed in Commons Lang 3.0.
*/
public static String clean(String str) {
return str == null ? EMPTY : str.trim();
}
/**
* <p>Removes control characters (char <= 32) from both
* ends of this String, handling <code>null</code> by returning
* <code>null</code>.</p>
*
* <p>The String is trimmed using {@link String#trim()}.
* Trim removes start and end characters <= 32.
* To strip whitespace use {@link #strip(String)}.</p>
*
* <p>To trim your choice of characters, use the
* {@link #strip(String, String)} methods.</p>
*
* <pre>
* StringUtils.trim(null) = null
* StringUtils.trim("") = ""
* StringUtils.trim(" ") = ""
* StringUtils.trim("abc") = "abc"
* StringUtils.trim(" abc ") = "abc"
* </pre>
*
* @param str the String to be trimmed, may be null
* @return the trimmed string, <code>null</code> if null String input
*/
public static String trim(String str) {
return str == null ? null : str.trim();
}
/**
* <p>Removes control characters (char <= 32) from both
* ends of this String returning <code>null</code> if the String is
* empty ("") after the trim or if it is <code>null</code>.
*
* <p>The String is trimmed using {@link String#trim()}.
* Trim removes start and end characters <= 32.
* To strip whitespace use {@link #stripToNull(String)}.</p>
*
* <pre>
* StringUtils.trimToNull(null) = null
* StringUtils.trimToNull("") = null
* StringUtils.trimToNull(" ") = null
* StringUtils.trimToNull("abc") = "abc"
* StringUtils.trimToNull(" abc ") = "abc"
* </pre>
*
* @param str the String to be trimmed, may be null
* @return the trimmed String,
* <code>null</code> if only chars <= 32, empty or null String input
* @since 2.0
*/
public static String trimToNull(String str) {
String ts = trim(str);
return isEmpty(ts) ? null : ts;
}
/**
* <p>Removes control characters (char <= 32) from both
* ends of this String returning an empty String ("") if the String
* is empty ("") after the trim or if it is <code>null</code>.
*
* <p>The String is trimmed using {@link String#trim()}.
* Trim removes start and end characters <= 32.
* To strip whitespace use {@link #stripToEmpty(String)}.</p>
*
* <pre>
* StringUtils.trimToEmpty(null) = ""
* StringUtils.trimToEmpty("") = ""
* StringUtils.trimToEmpty(" ") = ""
* StringUtils.trimToEmpty("abc") = "abc"
* StringUtils.trimToEmpty(" abc ") = "abc"
* </pre>
*
* @param str the String to be trimmed, may be null
* @return the trimmed String, or an empty String if <code>null</code> input
* @since 2.0
*/
public static String trimToEmpty(String str) {
return str == null ? EMPTY : str.trim();
}
// Stripping
//-----------------------------------------------------------------------
/**
* <p>Strips whitespace from the start and end of a String.</p>
*
* <p>This is similar to {@link #trim(String)} but removes whitespace.
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.strip(null) = null
* StringUtils.strip("") = ""
* StringUtils.strip(" ") = ""
* StringUtils.strip("abc") = "abc"
* StringUtils.strip(" abc") = "abc"
* StringUtils.strip("abc ") = "abc"
* StringUtils.strip(" abc ") = "abc"
* StringUtils.strip(" ab c ") = "ab c"
* </pre>
*
* @param str the String to remove whitespace from, may be null
* @return the stripped String, <code>null</code> if null String input
*/
public static String strip(String str) {
return strip(str, null);
}
/**
* <p>Strips whitespace from the start and end of a String returning
* <code>null</code> if the String is empty ("") after the strip.</p>
*
* <p>This is similar to {@link #trimToNull(String)} but removes whitespace.
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.strip(null) = null
* StringUtils.strip("") = null
* StringUtils.strip(" ") = null
* StringUtils.strip("abc") = "abc"
* StringUtils.strip(" abc") = "abc"
* StringUtils.strip("abc ") = "abc"
* StringUtils.strip(" abc ") = "abc"
* StringUtils.strip(" ab c ") = "ab c"
* </pre>
*
* @param str the String to be stripped, may be null
* @return the stripped String,
* <code>null</code> if whitespace, empty or null String input
* @since 2.0
*/
public static String stripToNull(String str) {
if (str == null) {
return null;
}
str = strip(str, null);
return str.length() == 0 ? null : str;
}
/**
* <p>Strips whitespace from the start and end of a String returning
* an empty String if <code>null</code> input.</p>
*
* <p>This is similar to {@link #trimToEmpty(String)} but removes whitespace.
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.strip(null) = ""
* StringUtils.strip("") = ""
* StringUtils.strip(" ") = ""
* StringUtils.strip("abc") = "abc"
* StringUtils.strip(" abc") = "abc"
* StringUtils.strip("abc ") = "abc"
* StringUtils.strip(" abc ") = "abc"
* StringUtils.strip(" ab c ") = "ab c"
* </pre>
*
* @param str the String to be stripped, may be null
* @return the trimmed String, or an empty String if <code>null</code> input
* @since 2.0
*/
public static String stripToEmpty(String str) {
return str == null ? EMPTY : strip(str, null);
}
/**
* <p>Strips any of a set of characters from the start and end of a String.
* This is similar to {@link String#trim()} but allows the characters
* to be stripped to be controlled.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* An empty string ("") input returns the empty string.</p>
*
* <p>If the stripChars String is <code>null</code>, whitespace is
* stripped as defined by {@link Character#isWhitespace(char)}.
* Alternatively use {@link #strip(String)}.</p>
*
* <pre>
* StringUtils.strip(null, *) = null
* StringUtils.strip("", *) = ""
* StringUtils.strip("abc", null) = "abc"
* StringUtils.strip(" abc", null) = "abc"
* StringUtils.strip("abc ", null) = "abc"
* StringUtils.strip(" abc ", null) = "abc"
* StringUtils.strip(" abcyx", "xyz") = " abc"
* </pre>
*
* @param str the String to remove characters from, may be null
* @param stripChars the characters to remove, null treated as whitespace
* @return the stripped String, <code>null</code> if null String input
*/
public static String strip(String str, String stripChars) {
if (isEmpty(str)) {
return str;
}
str = stripStart(str, stripChars);
return stripEnd(str, stripChars);
}
/**
* <p>Strips any of a set of characters from the start of a String.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* An empty string ("") input returns the empty string.</p>
*
* <p>If the stripChars String is <code>null</code>, whitespace is
* stripped as defined by {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.stripStart(null, *) = null
* StringUtils.stripStart("", *) = ""
* StringUtils.stripStart("abc", "") = "abc"
* StringUtils.stripStart("abc", null) = "abc"
* StringUtils.stripStart(" abc", null) = "abc"
* StringUtils.stripStart("abc ", null) = "abc "
* StringUtils.stripStart(" abc ", null) = "abc "
* StringUtils.stripStart("yxabc ", "xyz") = "abc "
* </pre>
*
* @param str the String to remove characters from, may be null
* @param stripChars the characters to remove, null treated as whitespace
* @return the stripped String, <code>null</code> if null String input
*/
public static String stripStart(String str, String stripChars) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return str;
}
int start = 0;
if (stripChars == null) {
while ((start != strLen) && Character.isWhitespace(str.charAt(start))) {
start++;
}
} else if (stripChars.length() == 0) {
return str;
} else {
while ((start != strLen) && (stripChars.indexOf(str.charAt(start)) != -1)) {
start++;
}
}
return str.substring(start);
}
/**
* <p>Strips any of a set of characters from the end of a String.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* An empty string ("") input returns the empty string.</p>
*
* <p>If the stripChars String is <code>null</code>, whitespace is
* stripped as defined by {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.stripEnd(null, *) = null
* StringUtils.stripEnd("", *) = ""
* StringUtils.stripEnd("abc", "") = "abc"
* StringUtils.stripEnd("abc", null) = "abc"
* StringUtils.stripEnd(" abc", null) = " abc"
* StringUtils.stripEnd("abc ", null) = "abc"
* StringUtils.stripEnd(" abc ", null) = " abc"
* StringUtils.stripEnd(" abcyx", "xyz") = " abc"
* </pre>
*
* @param str the String to remove characters from, may be null
* @param stripChars the characters to remove, null treated as whitespace
* @return the stripped String, <code>null</code> if null String input
*/
public static String stripEnd(String str, String stripChars) {
int end;
if (str == null || (end = str.length()) == 0) {
return str;
}
if (stripChars == null) {
while ((end != 0) && Character.isWhitespace(str.charAt(end - 1))) {
end--;
}
} else if (stripChars.length() == 0) {
return str;
} else {
while ((end != 0) && (stripChars.indexOf(str.charAt(end - 1)) != -1)) {
end--;
}
}
return str.substring(0, end);
}
// StripAll
//-----------------------------------------------------------------------
/**
* <p>Strips whitespace from the start and end of every String in an array.
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <p>A new array is returned each time, except for length zero.
* A <code>null</code> array will return <code>null</code>.
* An empty array will return itself.
* A <code>null</code> array entry will be ignored.</p>
*
* <pre>
* StringUtils.stripAll(null) = null
* StringUtils.stripAll([]) = []
* StringUtils.stripAll(["abc", " abc"]) = ["abc", "abc"]
* StringUtils.stripAll(["abc ", null]) = ["abc", null]
* </pre>
*
* @param strs the array to remove whitespace from, may be null
* @return the stripped Strings, <code>null</code> if null array input
*/
public static String[] stripAll(String[] strs) {
return stripAll(strs, null);
}
/**
* <p>Strips any of a set of characters from the start and end of every
* String in an array.</p>
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <p>A new array is returned each time, except for length zero.
* A <code>null</code> array will return <code>null</code>.
* An empty array will return itself.
* A <code>null</code> array entry will be ignored.
* A <code>null</code> stripChars will strip whitespace as defined by
* {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.stripAll(null, *) = null
* StringUtils.stripAll([], *) = []
* StringUtils.stripAll(["abc", " abc"], null) = ["abc", "abc"]
* StringUtils.stripAll(["abc ", null], null) = ["abc", null]
* StringUtils.stripAll(["abc ", null], "yz") = ["abc ", null]
* StringUtils.stripAll(["yabcz", null], "yz") = ["abc", null]
* </pre>
*
* @param strs the array to remove characters from, may be null
* @param stripChars the characters to remove, null treated as whitespace
* @return the stripped Strings, <code>null</code> if null array input
*/
public static String[] stripAll(String[] strs, String stripChars) {
int strsLen;
if (strs == null || (strsLen = strs.length) == 0) {
return strs;
}
String[] newArr = new String[strsLen];
for (int i = 0; i < strsLen; i++) {
newArr[i] = strip(strs[i], stripChars);
}
return newArr;
}
// Equals
//-----------------------------------------------------------------------
/**
* <p>Compares two Strings, returning <code>true</code> if they are equal.</p>
*
* <p><code>null</code>s are handled without exceptions. Two <code>null</code>
* references are considered to be equal. The comparison is case sensitive.</p>
*
* <pre>
* StringUtils.equals(null, null) = true
* StringUtils.equals(null, "abc") = false
* StringUtils.equals("abc", null) = false
* StringUtils.equals("abc", "abc") = true
* StringUtils.equals("abc", "ABC") = false
* </pre>
*
* @see java.lang.String#equals(Object)
* @param str1 the first String, may be null
* @param str2 the second String, may be null
* @return <code>true</code> if the Strings are equal, case sensitive, or
* both <code>null</code>
*/
public static boolean equals(String str1, String str2) {
return str1 == null ? str2 == null : str1.equals(str2);
}
/**
* <p>Compares two Strings, returning <code>true</code> if they are equal ignoring
* the case.</p>
*
* <p><code>null</code>s are handled without exceptions. Two <code>null</code>
* references are considered equal. Comparison is case insensitive.</p>
*
* <pre>
* StringUtils.equalsIgnoreCase(null, null) = true
* StringUtils.equalsIgnoreCase(null, "abc") = false
* StringUtils.equalsIgnoreCase("abc", null) = false
* StringUtils.equalsIgnoreCase("abc", "abc") = true
* StringUtils.equalsIgnoreCase("abc", "ABC") = true
* </pre>
*
* @see java.lang.String#equalsIgnoreCase(String)
* @param str1 the first String, may be null
* @param str2 the second String, may be null
* @return <code>true</code> if the Strings are equal, case insensitive, or
* both <code>null</code>
*/
public static boolean equalsIgnoreCase(String str1, String str2) {
return str1 == null ? str2 == null : str1.equalsIgnoreCase(str2);
}
// IndexOf
//-----------------------------------------------------------------------
/**
* <p>Finds the first index within a String, handling <code>null</code>.
* This method uses {@link String#indexOf(int)}.</p>
*
* <p>A <code>null</code> or empty ("") String will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.indexOf(null, *) = -1
* StringUtils.indexOf("", *) = -1
* StringUtils.indexOf("aabaabaa", 'a') = 0
* StringUtils.indexOf("aabaabaa", 'b') = 2
* </pre>
*
* @param str the String to check, may be null
* @param searchChar the character to find
* @return the first index of the search character,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int indexOf(String str, char searchChar) {
if (isEmpty(str)) {
return -1;
}
return str.indexOf(searchChar);
}
/**
* <p>Finds the first index within a String from a start position,
* handling <code>null</code>.
* This method uses {@link String#indexOf(int, int)}.</p>
*
* <p>A <code>null</code> or empty ("") String will return <code>-1</code>.
* A negative start position is treated as zero.
* A start position greater than the string length returns <code>-1</code>.</p>
*
* <pre>
* StringUtils.indexOf(null, *, *) = -1
* StringUtils.indexOf("", *, *) = -1
* StringUtils.indexOf("aabaabaa", 'b', 0) = 2
* StringUtils.indexOf("aabaabaa", 'b', 3) = 5
* StringUtils.indexOf("aabaabaa", 'b', 9) = -1
* StringUtils.indexOf("aabaabaa", 'b', -1) = 2
* </pre>
*
* @param str the String to check, may be null
* @param searchChar the character to find
* @param startPos the start position, negative treated as zero
* @return the first index of the search character,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int indexOf(String str, char searchChar, int startPos) {
if (isEmpty(str)) {
return -1;
}
return str.indexOf(searchChar, startPos);
}
/**
* <p>Finds the first index within a String, handling <code>null</code>.
* This method uses {@link String#indexOf(String)}.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.indexOf(null, *) = -1
* StringUtils.indexOf(*, null) = -1
* StringUtils.indexOf("", "") = 0
* StringUtils.indexOf("aabaabaa", "a") = 0
* StringUtils.indexOf("aabaabaa", "b") = 2
* StringUtils.indexOf("aabaabaa", "ab") = 1
* StringUtils.indexOf("aabaabaa", "") = 0
* </pre>
*
* @param str the String to check, may be null
* @param searchStr the String to find, may be null
* @return the first index of the search String,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int indexOf(String str, String searchStr) {
if (str == null || searchStr == null) {
return -1;
}
return str.indexOf(searchStr);
}
/**
* <p>Finds the n-th index within a String, handling <code>null</code>.
* This method uses {@link String#indexOf(String)}.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.ordinalIndexOf(null, *, *) = -1
* StringUtils.ordinalIndexOf(*, null, *) = -1
* StringUtils.ordinalIndexOf("", "", *) = 0
* StringUtils.ordinalIndexOf("aabaabaa", "a", 1) = 0
* StringUtils.ordinalIndexOf("aabaabaa", "a", 2) = 1
* StringUtils.ordinalIndexOf("aabaabaa", "b", 1) = 2
* StringUtils.ordinalIndexOf("aabaabaa", "b", 2) = 5
* StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1
* StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4
* StringUtils.ordinalIndexOf("aabaabaa", "", 1) = 0
* StringUtils.ordinalIndexOf("aabaabaa", "", 2) = 0
* </pre>
*
* @param str the String to check, may be null
* @param searchStr the String to find, may be null
* @param ordinal the n-th <code>searchStr</code> to find
* @return the n-th index of the search String,
* <code>-1</code> (<code>INDEX_NOT_FOUND</code>) if no match or <code>null</code> string
input
* @since 2.1
*/
public static int ordinalIndexOf(String str, String searchStr, int ordinal) {
if (str == null || searchStr == null || ordinal <= 0) {
return INDEX_NOT_FOUND;
}
if (searchStr.length() == 0) {
return 0;
}
int found = 0;
int index = INDEX_NOT_FOUND;
do {
index = str.indexOf(searchStr, index + 1);
if (index < 0) {
return index;
}
found++;
} while (found < ordinal);
return index;
}
/**
* <p>Finds the first index within a String, handling <code>null</code>.
* This method uses {@link String#indexOf(String, int)}.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A negative start position is treated as zero.
* An empty ("") search String always matches.
* A start position greater than the string length only matches
* an empty search String.</p>
*
* <pre>
* StringUtils.indexOf(null, *, *) = -1
* StringUtils.indexOf(*, null, *) = -1
* StringUtils.indexOf("", "", 0) = 0
* StringUtils.indexOf("aabaabaa", "a", 0) = 0
* StringUtils.indexOf("aabaabaa", "b", 0) = 2
* StringUtils.indexOf("aabaabaa", "ab", 0) = 1
* StringUtils.indexOf("aabaabaa", "b", 3) = 5
* StringUtils.indexOf("aabaabaa", "b", 9) = -1
* StringUtils.indexOf("aabaabaa", "b", -1) = 2
* StringUtils.indexOf("aabaabaa", "", 2) = 2
* StringUtils.indexOf("abc", "", 9) = 3
* </pre>
*
* @param str the String to check, may be null
* @param searchStr the String to find, may be null
* @param startPos the start position, negative treated as zero
* @return the first index of the search String,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int indexOf(String str, String searchStr, int startPos) {
if (str == null || searchStr == null) {
return -1;
}
// JDK1.2/JDK1.3 have a bug, when startPos > str.length for "", hence
if (searchStr.length() == 0 && startPos >= str.length()) {
return str.length();
}
return str.indexOf(searchStr, startPos);
}
// LastIndexOf
//-----------------------------------------------------------------------
/**
* <p>Finds the last index within a String, handling <code>null</code>.
* This method uses {@link String#lastIndexOf(int)}.</p>
*
* <p>A <code>null</code> or empty ("") String will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.lastIndexOf(null, *) = -1
* StringUtils.lastIndexOf("", *) = -1
* StringUtils.lastIndexOf("aabaabaa", 'a') = 7
* StringUtils.lastIndexOf("aabaabaa", 'b') = 5
* </pre>
*
* @param str the String to check, may be null
* @param searchChar the character to find
* @return the last index of the search character,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int lastIndexOf(String str, char searchChar) {
if (isEmpty(str)) {
return -1;
}
return str.lastIndexOf(searchChar);
}
/**
* <p>Finds the last index within a String from a start position,
* handling <code>null</code>.
* This method uses {@link String#lastIndexOf(int, int)}.</p>
*
* <p>A <code>null</code> or empty ("") String will return <code>-1</code>.
* A negative start position returns <code>-1</code>.
* A start position greater than the string length searches the whole string.</p>
*
* <pre>
* StringUtils.lastIndexOf(null, *, *) = -1
* StringUtils.lastIndexOf("", *, *) = -1
* StringUtils.lastIndexOf("aabaabaa", 'b', 8) = 5
* StringUtils.lastIndexOf("aabaabaa", 'b', 4) = 2
* StringUtils.lastIndexOf("aabaabaa", 'b', 0) = -1
* StringUtils.lastIndexOf("aabaabaa", 'b', 9) = 5
* StringUtils.lastIndexOf("aabaabaa", 'b', -1) = -1
* StringUtils.lastIndexOf("aabaabaa", 'a', 0) = 0
* </pre>
*
* @param str the String to check, may be null
* @param searchChar the character to find
* @param startPos the start position
* @return the last index of the search character,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int lastIndexOf(String str, char searchChar, int startPos) {
if (isEmpty(str)) {
return -1;
}
return str.lastIndexOf(searchChar, startPos);
}
/**
* <p>Finds the last index within a String, handling <code>null</code>.
* This method uses {@link String#lastIndexOf(String)}.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.lastIndexOf(null, *) = -1
* StringUtils.lastIndexOf(*, null) = -1
* StringUtils.lastIndexOf("", "") = 0
* StringUtils.lastIndexOf("aabaabaa", "a") = 0
* StringUtils.lastIndexOf("aabaabaa", "b") = 2
* StringUtils.lastIndexOf("aabaabaa", "ab") = 1
* StringUtils.lastIndexOf("aabaabaa", "") = 8
* </pre>
*
* @param str the String to check, may be null
* @param searchStr the String to find, may be null
* @return the last index of the search String,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int lastIndexOf(String str, String searchStr) {
if (str == null || searchStr == null) {
return -1;
}
return str.lastIndexOf(searchStr);
}
/**
* <p>Finds the first index within a String, handling <code>null</code>.
* This method uses {@link String#lastIndexOf(String, int)}.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A negative start position returns <code>-1</code>.
* An empty ("") search String always matches unless the start position is negative.
* A start position greater than the string length searches the whole string.</p>
*
* <pre>
* StringUtils.lastIndexOf(null, *, *) = -1
* StringUtils.lastIndexOf(*, null, *) = -1
* StringUtils.lastIndexOf("aabaabaa", "a", 8) = 7
* StringUtils.lastIndexOf("aabaabaa", "b", 8) = 5
* StringUtils.lastIndexOf("aabaabaa", "ab", 8) = 4
* StringUtils.lastIndexOf("aabaabaa", "b", 9) = 5
* StringUtils.lastIndexOf("aabaabaa", "b", -1) = -1
* StringUtils.lastIndexOf("aabaabaa", "a", 0) = 0
* StringUtils.lastIndexOf("aabaabaa", "b", 0) = -1
* </pre>
*
* @param str the String to check, may be null
* @param searchStr the String to find, may be null
* @param startPos the start position, negative treated as zero
* @return the first index of the search String,
* -1 if no match or <code>null</code> string input
* @since 2.0
*/
public static int lastIndexOf(String str, String searchStr, int startPos) {
if (str == null || searchStr == null) {
return -1;
}
return str.lastIndexOf(searchStr, startPos);
}
// Contains
//-----------------------------------------------------------------------
/**
* <p>Checks if String contains a search character, handling <code>null</code>.
* This method uses {@link String#indexOf(int)}.</p>
*
* <p>A <code>null</code> or empty ("") String will return <code>false</code>.</p>
*
* <pre>
* StringUtils.contains(null, *) = false
* StringUtils.contains("", *) = false
* StringUtils.contains("abc", 'a') = true
* StringUtils.contains("abc", 'z') = false
* </pre>
*
* @param str the String to check, may be null
* @param searchChar the character to find
* @return true if the String contains the search character,
* false if not or <code>null</code> string input
* @since 2.0
*/
public static boolean contains(String str, char searchChar) {
if (isEmpty(str)) {
return false;
}
return str.indexOf(searchChar) >= 0;
}
/**
* <p>Checks if String contains a search String, handling <code>null</code>.
* This method uses {@link String#indexOf(int)}.</p>
*
* <p>A <code>null</code> String will return <code>false</code>.</p>
*
* <pre>
* StringUtils.contains(null, *) = false
* StringUtils.contains(*, null) = false
* StringUtils.contains("", "") = true
* StringUtils.contains("abc", "") = true
* StringUtils.contains("abc", "a") = true
* StringUtils.contains("abc", "z") = false
* </pre>
*
* @param str the String to check, may be null
* @param searchStr the String to find, may be null
* @return true if the String contains the search String,
* false if not or <code>null</code> string input
* @since 2.0
*/
public static boolean contains(String str, String searchStr) {
if (str == null || searchStr == null) {
return false;
}
return str.indexOf(searchStr) >= 0;
}
// IndexOfAny chars
//-----------------------------------------------------------------------
/**
* <p>Search a String to find the first index of any
* character in the given set of characters.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A <code>null</code> or zero length search array will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.indexOfAny(null, *) = -1
* StringUtils.indexOfAny("", *) = -1
* StringUtils.indexOfAny(*, null) = -1
* StringUtils.indexOfAny(*, []) = -1
* StringUtils.indexOfAny("zzabyycdxx",['z','a']) = 0
* StringUtils.indexOfAny("zzabyycdxx",['b','y']) = 3
* StringUtils.indexOfAny("aba", ['z']) = -1
* </pre>
*
* @param str the String to check, may be null
* @param searchChars the chars to search for, may be null
* @return the index of any of the chars, -1 if no match or null input
* @since 2.0
*/
public static int indexOfAny(String str, char[] searchChars) {
if (isEmpty(str) || ArrayUtils.isEmpty(searchChars)) {
return -1;
}
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
for (int j = 0; j < searchChars.length; j++) {
if (searchChars[j] == ch) {
return i;
}
}
}
return -1;
}
/**
* <p>Search a String to find the first index of any
* character in the given set of characters.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A <code>null</code> search string will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.indexOfAny(null, *) = -1
* StringUtils.indexOfAny("", *) = -1
* StringUtils.indexOfAny(*, null) = -1
* StringUtils.indexOfAny(*, "") = -1
* StringUtils.indexOfAny("zzabyycdxx", "za") = 0
* StringUtils.indexOfAny("zzabyycdxx", "by") = 3
* StringUtils.indexOfAny("aba","z") = -1
* </pre>
*
* @param str the String to check, may be null
* @param searchChars the chars to search for, may be null
* @return the index of any of the chars, -1 if no match or null input
* @since 2.0
*/
public static int indexOfAny(String str, String searchChars) {
if (isEmpty(str) || isEmpty(searchChars)) {
return -1;
}
return indexOfAny(str, searchChars.toCharArray());
}
// IndexOfAnyBut chars
//-----------------------------------------------------------------------
/**
* <p>Search a String to find the first index of any
* character not in the given set of characters.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A <code>null</code> or zero length search array will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.indexOfAnyBut(null, *) = -1
* StringUtils.indexOfAnyBut("", *) = -1
* StringUtils.indexOfAnyBut(*, null) = -1
* StringUtils.indexOfAnyBut(*, []) = -1
* StringUtils.indexOfAnyBut("zzabyycdxx",'za') = 3
* StringUtils.indexOfAnyBut("zzabyycdxx", '') = 0
* StringUtils.indexOfAnyBut("aba", 'ab') = -1
* </pre>
*
* @param str the String to check, may be null
* @param searchChars the chars to search for, may be null
* @return the index of any of the chars, -1 if no match or null input
* @since 2.0
*/
public static int indexOfAnyBut(String str, char[] searchChars) {
if (isEmpty(str) || ArrayUtils.isEmpty(searchChars)) {
return -1;
}
outer : for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
for (int j = 0; j < searchChars.length; j++) {
if (searchChars[j] == ch) {
continue outer;
}
}
return i;
}
return -1;
}
/**
* <p>Search a String to find the first index of any
* character not in the given set of characters.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A <code>null</code> search string will return <code>-1</code>.</p>
*
* <pre>
* StringUtils.indexOfAnyBut(null, *) = -1
* StringUtils.indexOfAnyBut("", *) = -1
* StringUtils.indexOfAnyBut(*, null) = -1
* StringUtils.indexOfAnyBut(*, "") = -1
* StringUtils.indexOfAnyBut("zzabyycdxx", "za") = 3
* StringUtils.indexOfAnyBut("zzabyycdxx", "") = 0
* StringUtils.indexOfAnyBut("aba","ab") = -1
* </pre>
*
* @param str the String to check, may be null
* @param searchChars the chars to search for, may be null
* @return the index of any of the chars, -1 if no match or null input
* @since 2.0
*/
public static int indexOfAnyBut(String str, String searchChars) {
if (isEmpty(str) || isEmpty(searchChars)) {
return -1;
}
for (int i = 0; i < str.length(); i++) {
if (searchChars.indexOf(str.charAt(i)) < 0) {
return i;
}
}
return -1;
}
// ContainsOnly
//-----------------------------------------------------------------------
/**
* <p>Checks if the String contains only certain characters.</p>
*
* <p>A <code>null</code> String will return <code>false</code>.
* A <code>null</code> valid character array will return <code>false</code>.
* An empty String ("") always returns <code>true</code>.</p>
*
* <pre>
* StringUtils.containsOnly(null, *) = false
* StringUtils.containsOnly(*, null) = false
* StringUtils.containsOnly("", *) = true
* StringUtils.containsOnly("ab", '') = false
* StringUtils.containsOnly("abab", 'abc') = true
* StringUtils.containsOnly("ab1", 'abc') = false
* StringUtils.containsOnly("abz", 'abc') = false
* </pre>
*
* @param str the String to check, may be null
* @param valid an array of valid chars, may be null
* @return true if it only contains valid chars and is non-null
*/
public static boolean containsOnly(String str, char[] valid) {
// All these pre-checks are to maintain API with an older version
if ((valid == null) || (str == null)) {
return false;
}
if (str.length() == 0) {
return true;
}
if (valid.length == 0) {
return false;
}
return indexOfAnyBut(str, valid) == -1;
}
/**
* <p>Checks if the String contains only certain characters.</p>
*
* <p>A <code>null</code> String will return <code>false</code>.
* A <code>null</code> valid character String will return <code>false</code>.
* An empty String ("") always returns <code>true</code>.</p>
*
* <pre>
* StringUtils.containsOnly(null, *) = false
* StringUtils.containsOnly(*, null) = false
* StringUtils.containsOnly("", *) = true
* StringUtils.containsOnly("ab", "") = false
* StringUtils.containsOnly("abab", "abc") = true
* StringUtils.containsOnly("ab1", "abc") = false
* StringUtils.containsOnly("abz", "abc") = false
* </pre>
*
* @param str the String to check, may be null
* @param validChars a String of valid chars, may be null
* @return true if it only contains valid chars and is non-null
* @since 2.0
*/
public static boolean containsOnly(String str, String validChars) {
if (str == null || validChars == null) {
return false;
}
return containsOnly(str, validChars.toCharArray());
}
// ContainsNone
//-----------------------------------------------------------------------
/**
* <p>Checks that the String does not contain certain characters.</p>
*
* <p>A <code>null</code> String will return <code>true</code>.
* A <code>null</code> invalid character array will return <code>true</code>.
* An empty String ("") always returns true.</p>
*
* <pre>
* StringUtils.containsNone(null, *) = true
* StringUtils.containsNone(*, null) = true
* StringUtils.containsNone("", *) = true
* StringUtils.containsNone("ab", '') = true
* StringUtils.containsNone("abab", 'xyz') = true
* StringUtils.containsNone("ab1", 'xyz') = true
* StringUtils.containsNone("abz", 'xyz') = false
* </pre>
*
* @param str the String to check, may be null
* @param invalidChars an array of invalid chars, may be null
* @return true if it contains none of the invalid chars, or is null
* @since 2.0
*/
public static boolean containsNone(String str, char[] invalidChars) {
if (str == null || invalidChars == null) {
return true;
}
int strSize = str.length();
int validSize = invalidChars.length;
for (int i = 0; i < strSize; i++) {
char ch = str.charAt(i);
for (int j = 0; j < validSize; j++) {
if (invalidChars[j] == ch) {
return false;
}
}
}
return true;
}
/**
* <p>Checks that the String does not contain certain characters.</p>
*
* <p>A <code>null</code> String will return <code>true</code>.
* A <code>null</code> invalid character array will return <code>true</code>.
* An empty String ("") always returns true.</p>
*
* <pre>
* StringUtils.containsNone(null, *) = true
* StringUtils.containsNone(*, null) = true
* StringUtils.containsNone("", *) = true
* StringUtils.containsNone("ab", "") = true
* StringUtils.containsNone("abab", "xyz") = true
* StringUtils.containsNone("ab1", "xyz") = true
* StringUtils.containsNone("abz", "xyz") = false
* </pre>
*
* @param str the String to check, may be null
* @param invalidChars a String of invalid chars, may be null
* @return true if it contains none of the invalid chars, or is null
* @since 2.0
*/
public static boolean containsNone(String str, String invalidChars) {
if (str == null || invalidChars == null) {
return true;
}
return containsNone(str, invalidChars.toCharArray());
}
// IndexOfAny strings
//-----------------------------------------------------------------------
/**
* <p>Find the first index of any of a set of potential substrings.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A <code>null</code> or zero length search array will return <code>-1</code>.
* A <code>null</code> search array entry will be ignored, but a search
* array containing "" will return <code>0</code> if <code>str</code> is not
* null. This method uses {@link String#indexOf(String)}.</p>
*
* <pre>
* StringUtils.indexOfAny(null, *) = -1
* StringUtils.indexOfAny(*, null) = -1
* StringUtils.indexOfAny(*, []) = -1
* StringUtils.indexOfAny("zzabyycdxx", ["ab","cd"]) = 2
* StringUtils.indexOfAny("zzabyycdxx", ["cd","ab"]) = 2
* StringUtils.indexOfAny("zzabyycdxx", ["mn","op"]) = -1
* StringUtils.indexOfAny("zzabyycdxx", ["zab","aby"]) = 1
* StringUtils.indexOfAny("zzabyycdxx", [""]) = 0
* StringUtils.indexOfAny("", [""]) = 0
* StringUtils.indexOfAny("", ["a"]) = -1
* </pre>
*
* @param str the String to check, may be null
* @param searchStrs the Strings to search for, may be null
* @return the first index of any of the searchStrs in str, -1 if no match
*/
public static int indexOfAny(String str, String[] searchStrs) {
if ((str == null) || (searchStrs == null)) {
return -1;
}
int sz = searchStrs.length;
// String's can't have a MAX_VALUEth index.
int ret = Integer.MAX_VALUE;
int tmp = 0;
for (int i = 0; i < sz; i++) {
String search = searchStrs[i];
if (search == null) {
continue;
}
tmp = str.indexOf(search);
if (tmp == -1) {
continue;
}
if (tmp < ret) {
ret = tmp;
}
}
return (ret == Integer.MAX_VALUE) ? -1 : ret;
}
/**
* <p>Find the latest index of any of a set of potential substrings.</p>
*
* <p>A <code>null</code> String will return <code>-1</code>.
* A <code>null</code> search array will return <code>-1</code>.
* A <code>null</code> or zero length search array entry will be ignored,
* but a search array containing "" will return the length of <code>str</code>
* if <code>str</code> is not null. This method uses {@link String#indexOf(String)}</p>
*
* <pre>
* StringUtils.lastIndexOfAny(null, *) = -1
* StringUtils.lastIndexOfAny(*, null) = -1
* StringUtils.lastIndexOfAny(*, []) = -1
* StringUtils.lastIndexOfAny(*, [null]) = -1
* StringUtils.lastIndexOfAny("zzabyycdxx", ["ab","cd"]) = 6
* StringUtils.lastIndexOfAny("zzabyycdxx", ["cd","ab"]) = 6
* StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
* StringUtils.lastIndexOfAny("zzabyycdxx", ["mn","op"]) = -1
* StringUtils.lastIndexOfAny("zzabyycdxx", ["mn",""]) = 10
* </pre>
*
* @param str the String to check, may be null
* @param searchStrs the Strings to search for, may be null
* @return the last index of any of the Strings, -1 if no match
*/
public static int lastIndexOfAny(String str, String[] searchStrs) {
if ((str == null) || (searchStrs == null)) {
return -1;
}
int sz = searchStrs.length;
int ret = -1;
int tmp = 0;
for (int i = 0; i < sz; i++) {
String search = searchStrs[i];
if (search == null) {
continue;
}
tmp = str.lastIndexOf(search);
if (tmp > ret) {
ret = tmp;
}
}
return ret;
}
// Substring
//-----------------------------------------------------------------------
/**
* <p>Gets a substring from the specified String avoiding exceptions.</p>
*
* <p>A negative start position can be used to start <code>n</code>
* characters from the end of the String.</p>
*
* <p>A <code>null</code> String will return <code>null</code>.
* An empty ("") String will return "".</p>
*
* <pre>
* StringUtils.substring(null, *) = null
* StringUtils.substring("", *) = ""
* StringUtils.substring("abc", 0) = "abc"
* StringUtils.substring("abc", 2) = "c"
* StringUtils.substring("abc", 4) = ""
* StringUtils.substring("abc", -2) = "bc"
* StringUtils.substring("abc", -4) = "abc"
* </pre>
*
* @param str the String to get the substring from, may be null
* @param start the position to start from, negative means
* count back from the end of the String by this many characters
* @return substring from start position, <code>null</code> if null String input
*/
public static String substring(String str, int start) {
if (str == null) {
return null;
}
// handle negatives, which means last n characters
if (start < 0) {
start = str.length() + start; // remember start is negative
}
if (start < 0) {
start = 0;
}
if (start > str.length()) {
return EMPTY;
}
return str.substring(start);
}
/**
* <p>Gets a substring from the specified String avoiding exceptions.</p>
*
* <p>A negative start position can be used to start/end <code>n</code>
* characters from the end of the String.</p>
*
* <p>The returned substring starts with the character in the <code>start</code>
* position and ends before the <code>end</code> position. All position counting is
* zero-based -- i.e., to start at the beginning of the string use
* <code>start = 0</code>. Negative start and end positions can be used to
* specify offsets relative to the end of the String.</p>
*
* <p>If <code>start</code> is not strictly to the left of <code>end</code>, ""
* is returned.</p>
*
* <pre>
* StringUtils.substring(null, *, *) = null
* StringUtils.substring("", * , *) = "";
* StringUtils.substring("abc", 0, 2) = "ab"
* StringUtils.substring("abc", 2, 0) = ""
* StringUtils.substring("abc", 2, 4) = "c"
* StringUtils.substring("abc", 4, 6) = ""
* StringUtils.substring("abc", 2, 2) = ""
* StringUtils.substring("abc", -2, -1) = "b"
* StringUtils.substring("abc", -4, 2) = "ab"
* </pre>
*
* @param str the String to get the substring from, may be null
* @param start the position to start from, negative means
* count back from the end of the String by this many characters
* @param end the position to end at (exclusive), negative means
* count back from the end of the String by this many characters
* @return substring from start position to end positon,
* <code>null</code> if null String input
*/
public static String substring(String str, int start, int end) {
if (str == null) {
return null;
}
// handle negatives
if (end < 0) {
end = str.length() + end; // remember end is negative
}
if (start < 0) {
start = str.length() + start; // remember start is negative
}
// check length next
if (end > str.length()) {
end = str.length();
}
// if start is greater than end, return ""
if (start > end) {
return EMPTY;
}
if (start < 0) {
start = 0;
}
if (end < 0) {
end = 0;
}
return str.substring(start, end);
}
// Left/Right/Mid
//-----------------------------------------------------------------------
/**
* <p>Gets the leftmost <code>len</code> characters of a String.</p>
*
* <p>If <code>len</code> characters are not available, or the
* String is <code>null</code>, the String will be returned without
* an exception. An exception is thrown if len is negative.</p>
*
* <pre>
* StringUtils.left(null, *) = null
* StringUtils.left(*, -ve) = ""
* StringUtils.left("", *) = ""
* StringUtils.left("abc", 0) = ""
* StringUtils.left("abc", 2) = "ab"
* StringUtils.left("abc", 4) = "abc"
* </pre>
*
* @param str the String to get the leftmost characters from, may be null
* @param len the length of the required String, must be zero or positive
* @return the leftmost characters, <code>null</code> if null String input
*/
public static String left(String str, int len) {
if (str == null) {
return null;
}
if (len < 0) {
return EMPTY;
}
if (str.length() <= len) {
return str;
} else {
return str.substring(0, len);
}
}
/**
* <p>Gets the rightmost <code>len</code> characters of a String.</p>
*
* <p>If <code>len</code> characters are not available, or the String
* is <code>null</code>, the String will be returned without an
* an exception. An exception is thrown if len is negative.</p>
*
* <pre>
* StringUtils.right(null, *) = null
* StringUtils.right(*, -ve) = ""
* StringUtils.right("", *) = ""
* StringUtils.right("abc", 0) = ""
* StringUtils.right("abc", 2) = "bc"
* StringUtils.right("abc", 4) = "abc"
* </pre>
*
* @param str the String to get the rightmost characters from, may be null
* @param len the length of the required String, must be zero or positive
* @return the rightmost characters, <code>null</code> if null String input
*/
public static String right(String str, int len) {
if (str == null) {
return null;
}
if (len < 0) {
return EMPTY;
}
if (str.length() <= len) {
return str;
} else {
return str.substring(str.length() - len);
}
}
/**
* <p>Gets <code>len</code> characters from the middle of a String.</p>
*
* <p>If <code>len</code> characters are not available, the remainder
* of the String will be returned without an exception. If the
* String is <code>null</code>, <code>null</code> will be returned.
* An exception is thrown if len is negative.</p>
*
* <pre>
* StringUtils.mid(null, *, *) = null
* StringUtils.mid(*, *, -ve) = ""
* StringUtils.mid("", 0, *) = ""
* StringUtils.mid("abc", 0, 2) = "ab"
* StringUtils.mid("abc", 0, 4) = "abc"
* StringUtils.mid("abc", 2, 4) = "c"
* StringUtils.mid("abc", 4, 2) = ""
* StringUtils.mid("abc", -2, 2) = "ab"
* </pre>
*
* @param str the String to get the characters from, may be null
* @param pos the position to start from, negative treated as zero
* @param len the length of the required String, must be zero or positive
* @return the middle characters, <code>null</code> if null String input
*/
public static String mid(String str, int pos, int len) {
if (str == null) {
return null;
}
if (len < 0 || pos > str.length()) {
return EMPTY;
}
if (pos < 0) {
pos = 0;
}
if (str.length() <= (pos + len)) {
return str.substring(pos);
} else {
return str.substring(pos, pos + len);
}
}
// SubStringAfter/SubStringBefore
//-----------------------------------------------------------------------
/**
* <p>Gets the substring before the first occurrence of a separator.
* The separator is not returned.</p>
*
* <p>A <code>null</code> string input will return <code>null</code>.
* An empty ("") string input will return the empty string.
* A <code>null</code> separator will return the input string.</p>
*
* <pre>
* StringUtils.substringBefore(null, *) = null
* StringUtils.substringBefore("", *) = ""
* StringUtils.substringBefore("abc", "a") = ""
* StringUtils.substringBefore("abcba", "b") = "a"
* StringUtils.substringBefore("abc", "c") = "ab"
* StringUtils.substringBefore("abc", "d") = "abc"
* StringUtils.substringBefore("abc", "") = ""
* StringUtils.substringBefore("abc", null) = "abc"
* </pre>
*
* @param str the String to get a substring from, may be null
* @param separator the String to search for, may be null
* @return the substring before the first occurrence of the separator,
* <code>null</code> if null String input
* @since 2.0
*/
public static String substringBefore(String str, String separator) {
if (isEmpty(str) || separator == null) {
return str;
}
if (separator.length() == 0) {
return EMPTY;
}
int pos = str.indexOf(separator);
if (pos == -1) {
return str;
}
return str.substring(0, pos);
}
/**
* <p>Gets the substring after the first occurrence of a separator.
* The separator is not returned.</p>
*
* <p>A <code>null</code> string input will return <code>null</code>.
* An empty ("") string input will return the empty string.
* A <code>null</code> separator will return the empty string if the
* input string is not <code>null</code>.</p>
*
* <pre>
* StringUtils.substringAfter(null, *) = null
* StringUtils.substringAfter("", *) = ""
* StringUtils.substringAfter(*, null) = ""
* StringUtils.substringAfter("abc", "a") = "bc"
* StringUtils.substringAfter("abcba", "b") = "cba"
* StringUtils.substringAfter("abc", "c") = ""
* StringUtils.substringAfter("abc", "d") = ""
* StringUtils.substringAfter("abc", "") = "abc"
* </pre>
*
* @param str the String to get a substring from, may be null
* @param separator the String to search for, may be null
* @return the substring after the first occurrence of the separator,
* <code>null</code> if null String input
* @since 2.0
*/
public static String substringAfter(String str, String separator) {
if (isEmpty(str)) {
return str;
}
if (separator == null) {
return EMPTY;
}
int pos = str.indexOf(separator);
if (pos == -1) {
return EMPTY;
}
return str.substring(pos + separator.length());
}
/**
* <p>Gets the substring before the last occurrence of a separator.
* The separator is not returned.</p>
*
* <p>A <code>null</code> string input will return <code>null</code>.
* An empty ("") string input will return the empty string.
* An empty or <code>null</code> separator will return the input string.</p>
*
* <pre>
* StringUtils.substringBeforeLast(null, *) = null
* StringUtils.substringBeforeLast("", *) = ""
* StringUtils.substringBeforeLast("abcba", "b") = "abc"
* StringUtils.substringBeforeLast("abc", "c") = "ab"
* StringUtils.substringBeforeLast("a", "a") = ""
* StringUtils.substringBeforeLast("a", "z") = "a"
* StringUtils.substringBeforeLast("a", null) = "a"
* StringUtils.substringBeforeLast("a", "") = "a"
* </pre>
*
* @param str the String to get a substring from, may be null
* @param separator the String to search for, may be null
* @return the substring before the last occurrence of the separator,
* <code>null</code> if null String input
* @since 2.0
*/
public static String substringBeforeLast(String str, String separator) {
if (isEmpty(str) || isEmpty(separator)) {
return str;
}
int pos = str.lastIndexOf(separator);
if (pos == -1) {
return str;
}
return str.substring(0, pos);
}
/**
* <p>Gets the substring after the last occurrence of a separator.
* The separator is not returned.</p>
*
* <p>A <code>null</code> string input will return <code>null</code>.
* An empty ("") string input will return the empty string.
* An empty or <code>null</code> separator will return the empty string if
* the input string is not <code>null</code>.</p>
*
* <pre>
* StringUtils.substringAfterLast(null, *) = null
* StringUtils.substringAfterLast("", *) = ""
* StringUtils.substringAfterLast(*, "") = ""
* StringUtils.substringAfterLast(*, null) = ""
* StringUtils.substringAfterLast("abc", "a") = "bc"
* StringUtils.substringAfterLast("abcba", "b") = "a"
* StringUtils.substringAfterLast("abc", "c") = ""
* StringUtils.substringAfterLast("a", "a") = ""
* StringUtils.substringAfterLast("a", "z") = ""
* </pre>
*
* @param str the String to get a substring from, may be null
* @param separator the String to search for, may be null
* @return the substring after the last occurrence of the separator,
* <code>null</code> if null String input
* @since 2.0
*/
public static String substringAfterLast(String str, String separator) {
if (isEmpty(str)) {
return str;
}
if (isEmpty(separator)) {
return EMPTY;
}
int pos = str.lastIndexOf(separator);
if (pos == -1 || pos == (str.length() - separator.length())) {
return EMPTY;
}
return str.substring(pos + separator.length());
}
// Substring between
//-----------------------------------------------------------------------
/**
* <p>Gets the String that is nested in between two instances of the
* same String.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> tag returns <code>null</code>.</p>
*
* <pre>
* StringUtils.substringBetween(null, *) = null
* StringUtils.substringBetween("", "") = ""
* StringUtils.substringBetween("", "tag") = null
* StringUtils.substringBetween("tagabctag", null) = null
* StringUtils.substringBetween("tagabctag", "") = ""
* StringUtils.substringBetween("tagabctag", "tag") = "abc"
* </pre>
*
* @param str the String containing the substring, may be null
* @param tag the String before and after the substring, may be null
* @return the substring, <code>null</code> if no match
* @since 2.0
*/
public static String substringBetween(String str, String tag) {
return substringBetween(str, tag, tag);
}
/**
* <p>Gets the String that is nested in between two Strings.
* Only the first match is returned.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> open/close returns <code>null</code> (no match).
* An empty ("") open/close returns an empty string.</p>
*
* <pre>
* StringUtils.substringBetween(null, *, *) = null
* StringUtils.substringBetween("", "", "") = ""
* StringUtils.substringBetween("", "", "tag") = null
* StringUtils.substringBetween("", "tag", "tag") = null
* StringUtils.substringBetween("yabcz", null, null) = null
* StringUtils.substringBetween("yabcz", "", "") = ""
* StringUtils.substringBetween("yabcz", "y", "z") = "abc"
* StringUtils.substringBetween("yabczyabcz", "y", "z") = "abc"
* </pre>
*
* @param str the String containing the substring, may be null
* @param open the String before the substring, may be null
* @param close the String after the substring, may be null
* @return the substring, <code>null</code> if no match
* @since 2.0
*/
public static String substringBetween(String str, String open, String close) {
if (str == null || open == null || close == null) {
return null;
}
int start = str.indexOf(open);
if (start != -1) {
int end = str.indexOf(close, start + open.length());
if (end != -1) {
return str.substring(start + open.length(), end);
}
}
return null;
}
// Nested extraction
//-----------------------------------------------------------------------
/**
* <p>Gets the String that is nested in between two instances of the
* same String.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> tag returns <code>null</code>.</p>
*
* <pre>
* StringUtils.getNestedString(null, *) = null
* StringUtils.getNestedString("", "") = ""
* StringUtils.getNestedString("", "tag") = null
* StringUtils.getNestedString("tagabctag", null) = null
* StringUtils.getNestedString("tagabctag", "") = ""
* StringUtils.getNestedString("tagabctag", "tag") = "abc"
* </pre>
*
* @param str the String containing nested-string, may be null
* @param tag the String before and after nested-string, may be null
* @return the nested String, <code>null</code> if no match
* @deprecated Use the better named {@link #substringBetween(String, String)}.
* Method will be removed in Commons Lang 3.0.
*/
public static String getNestedString(String str, String tag) {
return substringBetween(str, tag, tag);
}
/**
* <p>Gets the String that is nested in between two Strings.
* Only the first match is returned.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> open/close returns <code>null</code> (no match).
* An empty ("") open/close returns an empty string.</p>
*
* <pre>
* StringUtils.getNestedString(null, *, *) = null
* StringUtils.getNestedString("", "", "") = ""
* StringUtils.getNestedString("", "", "tag") = null
* StringUtils.getNestedString("", "tag", "tag") = null
* StringUtils.getNestedString("yabcz", null, null) = null
* StringUtils.getNestedString("yabcz", "", "") = ""
* StringUtils.getNestedString("yabcz", "y", "z") = "abc"
* StringUtils.getNestedString("yabczyabcz", "y", "z") = "abc"
* </pre>
*
* @param str the String containing nested-string, may be null
* @param open the String before nested-string, may be null
* @param close the String after nested-string, may be null
* @return the nested String, <code>null</code> if no match
* @deprecated Use the better named {@link #substringBetween(String, String, String)}.
* Method will be removed in Commons Lang 3.0.
*/
public static String getNestedString(String str, String open, String close) {
return substringBetween(str, open, close);
}
// Splitting
//-----------------------------------------------------------------------
/**
* <p>Splits the provided text into an array, using whitespace as the
* separator.
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as one separator.
* For more control over the split use the StrTokenizer class.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.split(null) = null
* StringUtils.split("") = []
* StringUtils.split("abc def") = ["abc", "def"]
* StringUtils.split("abc def") = ["abc", "def"]
* StringUtils.split(" abc ") = ["abc"]
* </pre>
*
* @param str the String to parse, may be null
* @return an array of parsed Strings, <code>null</code> if null String input
*/
public static String[] split(String str) {
return split(str, null, -1);
}
/**
* <p>Splits the provided text into an array, separator specified.
* This is an alternative to using StringTokenizer.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as one separator.
* For more control over the split use the StrTokenizer class.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.split(null, *) = null
* StringUtils.split("", *) = []
* StringUtils.split("a.b.c", '.') = ["a", "b", "c"]
* StringUtils.split("a..b.c", '.') = ["a", "b", "c"]
* StringUtils.split("a:b:c", '.') = ["a:b:c"]
* StringUtils.split("a/tb/nc", null) = ["a", "b", "c"]
* StringUtils.split("a b c", ' ') = ["a", "b", "c"]
* </pre>
*
* @param str the String to parse, may be null
* @param separatorChar the character used as the delimiter,
* <code>null</code> splits on whitespace
* @return an array of parsed Strings, <code>null</code> if null String input
* @since 2.0
*/
public static String[] split(String str, char separatorChar) {
return splitWorker(str, separatorChar, false);
}
/**
* <p>Splits the provided text into an array, separators specified.
* This is an alternative to using StringTokenizer.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as one separator.
* For more control over the split use the StrTokenizer class.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> separatorChars splits on whitespace.</p>
*
* <pre>
* StringUtils.split(null, *) = null
* StringUtils.split("", *) = []
* StringUtils.split("abc def", null) = ["abc", "def"]
* StringUtils.split("abc def", " ") = ["abc", "def"]
* StringUtils.split("abc def", " ") = ["abc", "def"]
* StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
* </pre>
*
* @param str the String to parse, may be null
* @param separatorChars the characters used as the delimiters,
* <code>null</code> splits on whitespace
* @return an array of parsed Strings, <code>null</code> if null String input
*/
public static String[] split(String str, String separatorChars) {
return splitWorker(str, separatorChars, -1, false);
}
/**
* <p>Splits the provided text into an array with a maximum length,
* separators specified.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as one separator.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> separatorChars splits on whitespace.</p>
*
* <p>If more than <code>max</code> delimited substrings are found, the last
* returned string includes all characters after the first <code>max - 1</code>
* returned strings (including separator characters).</p>
*
* <pre>
* StringUtils.split(null, *, *) = null
* StringUtils.split("", *, *) = []
* StringUtils.split("ab de fg", null, 0) = ["ab", "cd", "ef"]
* StringUtils.split("ab de fg", null, 0) = ["ab", "cd", "ef"]
* StringUtils.split("ab:cd:ef", ":", 0) = ["ab", "cd", "ef"]
* StringUtils.split("ab:cd:ef", ":", 2) = ["ab", "cd:ef"]
* </pre>
*
* @param str the String to parse, may be null
* @param separatorChars the characters used as the delimiters,
* <code>null</code> splits on whitespace
* @param max the maximum number of elements to include in the
* array. A zero or negative value implies no limit
* @return an array of parsed Strings, <code>null</code> if null String input
*/
public static String[] split(String str, String separatorChars, int max) {
return splitWorker(str, separatorChars, max, false);
}
/**
* <p>Splits the provided text into an array, separator string specified.</p>
*
* <p>The separator(s) will not be included in the returned String array.
* Adjacent separators are treated as one separator.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> separator splits on whitespace.</p>
*
* <pre>
* StringUtils.split(null, *) = null
* StringUtils.split("", *) = []
* StringUtils.split("ab de fg", null) = ["ab", "de", "fg"]
* StringUtils.split("ab de fg", null) = ["ab", "de", "fg"]
* StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"]
* StringUtils.split("abstemiouslyaeiouyabstemiously", "aeiouy") = ["bst", "m", "sl", "bst",
"m", "sl"]
* StringUtils.split("abstemiouslyaeiouyabstemiously", "aeiouy") = ["abstemiously",
"abstemiously"]
* </pre>
*
* @param str the String to parse, may be null
* @param separator String containing the String to be used as a delimiter,
* <code>null</code> splits on whitespace
* @return an array of parsed Strings, <code>null</code> if null String was input
*/
public static String[] splitByWholeSeparator(String str, String separator) {
return splitByWholeSeparator( str, separator, -1 ) ;
}
/**
* <p>Splits the provided text into an array, separator string specified.
* Returns a maximum of <code>max</code> substrings.</p>
*
* <p>The separator(s) will not be included in the returned String array.
* Adjacent separators are treated as one separator.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> separator splits on whitespace.</p>
*
* <pre>
* StringUtils.splitByWholeSeparator(null, *, *) = null
* StringUtils.splitByWholeSeparator("", *, *) = []
* StringUtils.splitByWholeSeparator("ab de fg", null, 0) = ["ab", "de", "fg"]
* StringUtils.splitByWholeSeparator("ab de fg", null, 0) = ["ab", "de", "fg"]
* StringUtils.splitByWholeSeparator("ab:cd:ef", ":", 2) = ["ab", "cd"]
* StringUtils.splitByWholeSeparator("abstemiouslyaeiouyabstemiously", "aeiouy", 2) = ["bst",
"m"]
* StringUtils.splitByWholeSeparator("abstemiouslyaeiouyabstemiously", "aeiouy", 2) =
["abstemiously", "abstemiously"]
* </pre>
*
* @param str the String to parse, may be null
* @param separator String containing the String to be used as a delimiter,
* <code>null</code> splits on whitespace
* @param max the maximum number of elements to include in the returned
* array. A zero or negative value implies no limit.
* @return an array of parsed Strings, <code>null</code> if null String was input
*/
public static String[] splitByWholeSeparator( String str, String separator, int max ) {
if (str == null) {
return null;
}
int len = str.length() ;
if (len == 0) {
return ArrayUtils.EMPTY_STRING_ARRAY;
}
if ( ( separator == null ) || ( "".equals( separator ) ) ) {
// Split on whitespace.
return split( str, null, max ) ;
}
int separatorLength = separator.length() ;
ArrayList substrings = new ArrayList() ;
int numberOfSubstrings = 0 ;
int beg = 0 ;
int end = 0 ;
while ( end < len ) {
end = str.indexOf( separator, beg ) ;
if ( end > -1 ) {
if ( end > beg ) {
numberOfSubstrings += 1 ;
if ( numberOfSubstrings == max ) {
end = len ;
substrings.add( str.substring( beg ) ) ;
} else {
// The following is OK, because String.substring( beg, end ) excludes
// the character at the position 'end'.
substrings.add( str.substring( beg, end ) ) ;
// Set the starting point for the next search.
// The following is equivalent to beg = end + (separatorLength - 1) + 1,
// which is the right calculation:
beg = end + separatorLength ;
}
} else {
// We found a consecutive occurrence of the separator, so skip it.
beg = end + separatorLength ;
}
} else {
// String.substring( beg ) goes from 'beg' to the end of the String.
substrings.add( str.substring( beg ) ) ;
end = len ;
}
}
return (String[]) substrings.toArray( new String[substrings.size()] ) ;
}
//-----------------------------------------------------------------------
/**
* <p>Splits the provided text into an array, using whitespace as the
* separator, preserving all tokens, including empty tokens created by
* adjacent separators. This is an alternative to using StringTokenizer.
* Whitespace is defined by {@link Character#isWhitespace(char)}.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as separators for empty tokens.
* For more control over the split use the StrTokenizer class.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.splitPreserveAllTokens(null) = null
* StringUtils.splitPreserveAllTokens("") = []
* StringUtils.splitPreserveAllTokens("abc def") = ["abc", "def"]
* StringUtils.splitPreserveAllTokens("abc def") = ["abc", "", "def"]
* StringUtils.splitPreserveAllTokens(" abc ") = ["", "abc", ""]
* </pre>
*
* @param str the String to parse, may be <code>null</code>
* @return an array of parsed Strings, <code>null</code> if null String input
* @since 2.1
*/
public static String[] splitPreserveAllTokens(String str) {
return splitWorker(str, null, -1, true);
}
/**
* <p>Splits the provided text into an array, separator specified,
* preserving all tokens, including empty tokens created by adjacent
* separators. This is an alternative to using StringTokenizer.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as separators for empty tokens.
* For more control over the split use the StrTokenizer class.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.splitPreserveAllTokens(null, *) = null
* StringUtils.splitPreserveAllTokens("", *) = []
* StringUtils.splitPreserveAllTokens("a.b.c", '.') = ["a", "b", "c"]
* StringUtils.splitPreserveAllTokens("a..b.c", '.') = ["a", "b", "c"]
* StringUtils.splitPreserveAllTokens("a:b:c", '.') = ["a:b:c"]
* StringUtils.splitPreserveAllTokens("a/tb/nc", null) = ["a", "b", "c"]
* StringUtils.splitPreserveAllTokens("a b c", ' ') = ["a", "b", "c"]
* StringUtils.splitPreserveAllTokens("a b c ", ' ') = ["a", "b", "c", ""]
* StringUtils.splitPreserveAllTokens("a b c ", ' ') = ["a", "b", "c", "", ""]
* StringUtils.splitPreserveAllTokens(" a b c", ' ') = ["", a", "b", "c"]
* StringUtils.splitPreserveAllTokens(" a b c", ' ') = ["", "", a", "b", "c"]
* StringUtils.splitPreserveAllTokens(" a b c ", ' ') = ["", a", "b", "c", ""]
* </pre>
*
* @param str the String to parse, may be <code>null</code>
* @param separatorChar the character used as the delimiter,
* <code>null</code> splits on whitespace
* @return an array of parsed Strings, <code>null</code> if null String input
* @since 2.1
*/
public static String[] splitPreserveAllTokens(String str, char separatorChar) {
return splitWorker(str, separatorChar, true);
}
/**
* Performs the logic for the <code>split</code> and
* <code>splitPreserveAllTokens</code> methods that do not return a
* maximum array length.
*
* @param str the String to parse, may be <code>null</code>
* @param separatorChar the separate character
* @param preserveAllTokens if <code>true</code>, adjacent separators are
* treated as empty token separators; if <code>false</code>, adjacent
* separators are treated as one separator.
* @return an array of parsed Strings, <code>null</code> if null String input
*/
private static String[] splitWorker(String str, char separatorChar, boolean preserveAllTokens)
{
// Performance tuned for 2.0 (JDK1.4)
if (str == null) {
return null;
}
int len = str.length();
if (len == 0) {
return ArrayUtils.EMPTY_STRING_ARRAY;
}
List list = new ArrayList();
int i = 0, start = 0;
boolean match = false;
boolean lastMatch = false;
while (i < len) {
if (str.charAt(i) == separatorChar) {
if (match || preserveAllTokens) {
list.add(str.substring(start, i));
match = false;
lastMatch = true;
}
start = ++i;
continue;
} else {
lastMatch = false;
}
match = true;
i++;
}
if (match || (preserveAllTokens && lastMatch)) {
list.add(str.substring(start, i));
}
return (String[]) list.toArray(new String[list.size()]);
}
/**
* <p>Splits the provided text into an array, separators specified,
* preserving all tokens, including empty tokens created by adjacent
* separators. This is an alternative to using StringTokenizer.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as separators for empty tokens.
* For more control over the split use the StrTokenizer class.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> separatorChars splits on whitespace.</p>
*
* <pre>
* StringUtils.splitPreserveAllTokens(null, *) = null
* StringUtils.splitPreserveAllTokens("", *) = []
* StringUtils.splitPreserveAllTokens("abc def", null) = ["abc", "def"]
* StringUtils.splitPreserveAllTokens("abc def", " ") = ["abc", "def"]
* StringUtils.splitPreserveAllTokens("abc def", " ") = ["abc", "", def"]
* StringUtils.splitPreserveAllTokens("ab:cd:ef", ":") = ["ab", "cd", "ef"]
* StringUtils.splitPreserveAllTokens("ab:cd:ef:", ":") = ["ab", "cd", "ef", ""]
* StringUtils.splitPreserveAllTokens("ab:cd:ef::", ":") = ["ab", "cd", "ef", "", ""]
* StringUtils.splitPreserveAllTokens("ab::cd:ef", ":") = ["ab", "", cd", "ef"]
* StringUtils.splitPreserveAllTokens(":cd:ef", ":") = ["", cd", "ef"]
* StringUtils.splitPreserveAllTokens("::cd:ef", ":") = ["", "", cd", "ef"]
* StringUtils.splitPreserveAllTokens(":cd:ef:", ":") = ["", cd", "ef", ""]
* </pre>
*
* @param str the String to parse, may be <code>null</code>
* @param separatorChars the characters used as the delimiters,
* <code>null</code> splits on whitespace
* @return an array of parsed Strings, <code>null</code> if null String input
* @since 2.1
*/
public static String[] splitPreserveAllTokens(String str, String separatorChars) {
return splitWorker(str, separatorChars, -1, true);
}
/**
* <p>Splits the provided text into an array with a maximum length,
* separators specified, preserving all tokens, including empty tokens
* created by adjacent separators.</p>
*
* <p>The separator is not included in the returned String array.
* Adjacent separators are treated as separators for empty tokens.
* Adjacent separators are treated as one separator.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.
* A <code>null</code> separatorChars splits on whitespace.</p>
*
* <p>If more than <code>max</code> delimited substrings are found, the last
* returned string includes all characters after the first <code>max - 1</code>
* returned strings (including separator characters).</p>
*
* <pre>
* StringUtils.splitPreserveAllTokens(null, *, *) = null
* StringUtils.splitPreserveAllTokens("", *, *) = []
* StringUtils.splitPreserveAllTokens("ab de fg", null, 0) = ["ab", "cd", "ef"]
* StringUtils.splitPreserveAllTokens("ab de fg", null, 0) = ["ab", "cd", "ef"]
* StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 0) = ["ab", "cd", "ef"]
* StringUtils.splitPreserveAllTokens("ab:cd:ef", ":", 2) = ["ab", "cd:ef"]
* StringUtils.splitPreserveAllTokens("ab de fg", null, 2) = ["ab", " de fg"]
* StringUtils.splitPreserveAllTokens("ab de fg", null, 3) = ["ab", "", " de fg"]
* StringUtils.splitPreserveAllTokens("ab de fg", null, 4) = ["ab", "", "", "de fg"]
* </pre>
*
* @param str the String to parse, may be <code>null</code>
* @param separatorChars the characters used as the delimiters,
* <code>null</code> splits on whitespace
* @param max the maximum number of elements to include in the
* array. A zero or negative value implies no limit
* @return an array of parsed Strings, <code>null</code> if null String input
* @since 2.1
*/
public static String[] splitPreserveAllTokens(String str, String separatorChars, int max) {
return splitWorker(str, separatorChars, max, true);
}
/**
* Performs the logic for the <code>split</code> and
* <code>splitPreserveAllTokens</code> methods that return a maximum array
* length.
*
* @param str the String to parse, may be <code>null</code>
* @param separatorChars the separate character
* @param max the maximum number of elements to include in the
* array. A zero or negative value implies no limit.
* @param preserveAllTokens if <code>true</code>, adjacent separators are
* treated as empty token separators; if <code>false</code>, adjacent
* separators are treated as one separator.
* @return an array of parsed Strings, <code>null</code> if null String input
*/
private static String[] splitWorker(String str, String separatorChars, int max, boolean
preserveAllTokens) {
// Performance tuned for 2.0 (JDK1.4)
// Direct code is quicker than StringTokenizer.
// Also, StringTokenizer uses isSpace() not isWhitespace()
if (str == null) {
return null;
}
int len = str.length();
if (len == 0) {
return ArrayUtils.EMPTY_STRING_ARRAY;
}
List list = new ArrayList();
int sizePlus1 = 1;
int i = 0, start = 0;
boolean match = false;
boolean lastMatch = false;
if (separatorChars == null) {
// Null separator means use whitespace
while (i < len) {
if (Character.isWhitespace(str.charAt(i))) {
if (match || preserveAllTokens) {
lastMatch = true;
if (sizePlus1++ == max) {
i = len;
lastMatch = false;
}
list.add(str.substring(start, i));
match = false;
}
start = ++i;
continue;
} else {
lastMatch = false;
}
match = true;
i++;
}
} else if (separatorChars.length() == 1) {
// Optimise 1 character case
char sep = separatorChars.charAt(0);
while (i < len) {
if (str.charAt(i) == sep) {
if (match || preserveAllTokens) {
lastMatch = true;
if (sizePlus1++ == max) {
i = len;
lastMatch = false;
}
list.add(str.substring(start, i));
match = false;
}
start = ++i;
continue;
} else {
lastMatch = false;
}
match = true;
i++;
}
} else {
// standard case
while (i < len) {
if (separatorChars.indexOf(str.charAt(i)) >= 0) {
if (match || preserveAllTokens) {
lastMatch = true;
if (sizePlus1++ == max) {
i = len;
lastMatch = false;
}
list.add(str.substring(start, i));
match = false;
}
start = ++i;
continue;
} else {
lastMatch = false;
}
match = true;
i++;
}
}
if (match || (preserveAllTokens && lastMatch)) {
list.add(str.substring(start, i));
}
return (String[]) list.toArray(new String[list.size()]);
}
// Joining
//-----------------------------------------------------------------------
/**
* <p>Concatenates elements of an array into a single String.
* Null objects or empty strings within the array are represented by
* empty strings.</p>
*
* <pre>
* StringUtils.concatenate(null) = null
* StringUtils.concatenate([]) = ""
* StringUtils.concatenate([null]) = ""
* StringUtils.concatenate(["a", "b", "c"]) = "abc"
* StringUtils.concatenate([null, "", "a"]) = "a"
* </pre>
*
* @param array the array of values to concatenate, may be null
* @return the concatenated String, <code>null</code> if null array input
* @deprecated Use the better named {@link #join(Object[])} instead.
* Method will be removed in Commons Lang 3.0.
*/
public static String concatenate(Object[] array) {
return join(array, null);
}
/**
* <p>Joins the elements of the provided array into a single String
* containing the provided list of elements.</p>
*
* <p>No separator is added to the joined String.
* Null objects or empty strings within the array are represented by
* empty strings.</p>
*
* <pre>
* StringUtils.join(null) = null
* StringUtils.join([]) = ""
* StringUtils.join([null]) = ""
* StringUtils.join(["a", "b", "c"]) = "abc"
* StringUtils.join([null, "", "a"]) = "a"
* </pre>
*
* @param array the array of values to join together, may be null
* @return the joined String, <code>null</code> if null array input
* @since 2.0
*/
public static String join(Object[] array) {
return join(array, null);
}
/**
* <p>Joins the elements of the provided array into a single String
* containing the provided list of elements.</p>
*
* <p>No delimiter is added before or after the list.
* Null objects or empty strings within the array are represented by
* empty strings.</p>
*
* <pre>
* StringUtils.join(null, *) = null
* StringUtils.join([], *) = ""
* StringUtils.join([null], *) = ""
* StringUtils.join(["a", "b", "c"], ';') = "a;b;c"
* StringUtils.join(["a", "b", "c"], null) = "abc"
* StringUtils.join([null, "", "a"], ';') = ";;a"
* </pre>
*
* @param array the array of values to join together, may be null
* @param separator the separator character to use
* @return the joined String, <code>null</code> if null array input
* @since 2.0
*/
public static String join(Object[] array, char separator) {
if (array == null) {
return null;
}
int arraySize = array.length;
int bufSize = (arraySize == 0 ? 0 : ((array[0] == null ? 16 : array[0].toString().length())
+ 1) * arraySize);
StringBuffer buf = new StringBuffer(bufSize);
for (int i = 0; i < arraySize; i++) {
if (i > 0) {
buf.append(separator);
}
if (array[i] != null) {
buf.append(array[i]);
}
}
return buf.toString();
}
/**
* <p>Joins the elements of the provided array into a single String
* containing the provided list of elements.</p>
*
* <p>No delimiter is added before or after the list.
* A <code>null</code> separator is the same as an empty String ("").
* Null objects or empty strings within the array are represented by
* empty strings.</p>
*
* <pre>
* StringUtils.join(null, *) = null
* StringUtils.join([], *) = ""
* StringUtils.join([null], *) = ""
* StringUtils.join(["a", "b", "c"], "--") = "a--b--c"
* StringUtils.join(["a", "b", "c"], null) = "abc"
* StringUtils.join(["a", "b", "c"], "") = "abc"
* StringUtils.join([null, "", "a"], ',') = ",,a"
* </pre>
*
* @param array the array of values to join together, may be null
* @param separator the separator character to use, null treated as ""
* @return the joined String, <code>null</code> if null array input
*/
public static String join(Object[] array, String separator) {
if (array == null) {
return null;
}
if (separator == null) {
separator = EMPTY;
}
int arraySize = array.length;
// ArraySize == 0: Len = 0
// ArraySize > 0: Len = NofStrings *(len(firstString) + len(separator))
// (Assuming that all Strings are roughly equally long)
int bufSize =
((arraySize == 0)
? 0
: arraySize
* ((array[0] == null ? 16 : array[0].toString().length())
+ separator.length()));
StringBuffer buf = new StringBuffer(bufSize);
for (int i = 0; i < arraySize; i++) {
if (i > 0) {
buf.append(separator);
}
if (array[i] != null) {
buf.append(array[i]);
}
}
return buf.toString();
}
/**
* <p>Joins the elements of the provided <code>Iterator</code> into
* a single String containing the provided elements.</p>
*
* <p>No delimiter is added before or after the list. Null objects or empty
* strings within the iteration are represented by empty strings.</p>
*
* <p>See the examples here: {@link #join(Object[],char)}. </p>
*
* @param iterator the <code>Iterator</code> of values to join together, may be null
* @param separator the separator character to use
* @return the joined String, <code>null</code> if null iterator input
* @since 2.0
*/
public static String join(Iterator iterator, char separator) {
if (iterator == null) {
return null;
}
StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small
while (iterator.hasNext()) {
Object obj = iterator.next();
if (obj != null) {
buf.append(obj);
}
if (iterator.hasNext()) {
buf.append(separator);
}
}
return buf.toString();
}
/**
* <p>Joins the elements of the provided <code>Iterator</code> into
* a single String containing the provided elements.</p>
*
* <p>No delimiter is added before or after the list.
* A <code>null</code> separator is the same as an empty String ("").</p>
*
* <p>See the examples here: {@link #join(Object[],String)}. </p>
*
* @param iterator the <code>Iterator</code> of values to join together, may be null
* @param separator the separator character to use, null treated as ""
* @return the joined String, <code>null</code> if null iterator input
*/
public static String join(Iterator iterator, String separator) {
if (iterator == null) {
return null;
}
StringBuffer buf = new StringBuffer(256); // Java default is 16, probably too small
while (iterator.hasNext()) {
Object obj = iterator.next();
if (obj != null) {
buf.append(obj);
}
if ((separator != null) && iterator.hasNext()) {
buf.append(separator);
}
}
return buf.toString();
}
// Delete
//-----------------------------------------------------------------------
/**
* <p>Deletes all 'space' characters from a String as defined by
* {@link Character#isSpace(char)}.</p>
*
* <p>This is the only StringUtils method that uses the
* <code>isSpace</code> definition. You are advised to use
* {@link #deleteWhitespace(String)} instead as whitespace is much
* better localized.</p>
*
* <pre>
* StringUtils.deleteSpaces(null) = null
* StringUtils.deleteSpaces("") = ""
* StringUtils.deleteSpaces("abc") = "abc"
* StringUtils.deleteSpaces(" /t abc /n ") = "abc"
* StringUtils.deleteSpaces("ab c") = "abc"
* StringUtils.deleteSpaces("a/nb/tc ") = "abc"
* </pre>
*
* <p>Spaces are defined as <code>{' ', '/t', '/r', '/n', '/b'}</code>
* in line with the deprecated <code>isSpace</code> method.</p>
*
* @param str the String to delete spaces from, may be null
* @return the String without 'spaces', <code>null</code> if null String input
* @deprecated Use the better localized {@link #deleteWhitespace(String)}.
* Method will be removed in Commons Lang 3.0.
*/
public static String deleteSpaces(String str) {
if (str == null) {
return null;
}
return CharSetUtils.delete(str, " /t/r/n/b");
}
/**
* <p>Deletes all whitespaces from a String as defined by
* {@link Character#isWhitespace(char)}.</p>
*
* <pre>
* StringUtils.deleteWhitespace(null) = null
* StringUtils.deleteWhitespace("") = ""
* StringUtils.deleteWhitespace("abc") = "abc"
* StringUtils.deleteWhitespace(" ab c ") = "abc"
* </pre>
*
* @param str the String to delete whitespace from, may be null
* @return the String without whitespaces, <code>null</code> if null String input
*/
public static String deleteWhitespace(String str) {
if (isEmpty(str)) {
return str;
}
int sz = str.length();
char[] chs = new char[sz];
int count = 0;
for (int i = 0; i < sz; i++) {
if (!Character.isWhitespace(str.charAt(i))) {
chs[count++] = str.charAt(i);
}
}
if (count == sz) {
return str;
}
return new String(chs, 0, count);
}
// Remove
//-----------------------------------------------------------------------
/**
* <p>Removes a substring only if it is at the begining of a source string,
* otherwise returns the source string.</p>
*
* <p>A <code>null</code> source string will return <code>null</code>.
* An empty ("") source string will return the empty string.
* A <code>null</code> search string will return the source string.</p>
*
* <pre>
* StringUtils.removeStart(null, *) = null
* StringUtils.removeStart("", *) = ""
* StringUtils.removeStart(*, null) = *
* StringUtils.removeStart("www.domain.com", "www.") = "domain.com"
* StringUtils.removeStart("domain.com", "www.") = "domain.com"
* StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com"
* StringUtils.removeStart("abc", "") = "abc"
* </pre>
*
* @param str the source String to search, may be null
* @param remove the String to search for and remove, may be null
* @return the substring with the string removed if found,
* <code>null</code> if null String input
* @since 2.1
*/
public static String removeStart(String str, String remove) {
if (isEmpty(str) || isEmpty(remove)) {
return str;
}
if (str.startsWith(remove)){
return str.substring(remove.length());
}
return str;
}
/**
* <p>Removes a substring only if it is at the end of a source string,
* otherwise returns the source string.</p>
*
* <p>A <code>null</code> source string will return <code>null</code>.
* An empty ("") source string will return the empty string.
* A <code>null</code> search string will return the source string.</p>
*
* <pre>
* StringUtils.removeEnd(null, *) = null
* StringUtils.removeEnd("", *) = ""
* StringUtils.removeEnd(*, null) = *
* StringUtils.removeEnd("www.domain.com", ".com.") = "www,domain"
* StringUtils.removeEnd("www.domain.com", ".com") = "www.domain"
* StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
* StringUtils.removeEnd("abc", "") = "abc"
* </pre>
*
* @param str the source String to search, may be null
* @param remove the String to search for and remove, may be null
* @return the substring with the string removed if found,
* <code>null</code> if null String input
* @since 2.1
*/
public static String removeEnd(String str, String remove) {
if (isEmpty(str) || isEmpty(remove)) {
return str;
}
if (str.endsWith(remove)) {
return str.substring(0, str.length() - remove.length());
}
return str;
}
/**
* <p>Removes all occurances of a substring from within the source string.</p>
*
* <p>A <code>null</code> source string will return <code>null</code>.
* An empty ("") source string will return the empty string.
* A <code>null</code> remove string will return the source string.
* An empty ("") remove string will return the source string.</p>
*
* <pre>
* StringUtils.remove(null, *) = null
* StringUtils.remove("", *) = ""
* StringUtils.remove(*, null) = *
* StringUtils.remove(*, "") = *
* StringUtils.remove("queued", "ue") = "qd"
* StringUtils.remove("queued", "zz") = "queued"
* </pre>
*
* @param str the source String to search, may be null
* @param remove the String to search for and remove, may be null
* @return the substring with the string removed if found,
* <code>null</code> if null String input
* @since 2.1
*/
public static String remove(String str, String remove) {
if (isEmpty(str) || isEmpty(remove)) {
return str;
}
return replace(str, remove, "", -1);
}
/**
* <p>Removes all occurances of a character from within the source string.</p>
*
* <p>A <code>null</code> source string will return <code>null</code>.
* An empty ("") source string will return the empty string.</p>
*
* <pre>
* StringUtils.remove(null, *) = null
* StringUtils.remove("", *) = ""
* StringUtils.remove("queued", 'u') = "qeed"
* StringUtils.remove("queued", 'z') = "queued"
* </pre>
*
* @param str the source String to search, may be null
* @param remove the char to search for and remove, may be null
* @return the substring with the char removed if found,
* <code>null</code> if null String input
* @since 2.1
*/
public static String remove(String str, char remove) {
if (isEmpty(str) || str.indexOf(remove) == -1) {
return str;
}
char[] chars = str.toCharArray();
int pos = 0;
for (int i = 0; i < chars.length; i++) {
if (chars[i] != remove) {
chars[pos++] = chars[i];
}
}
return new String(chars, 0, pos);
}
// Replacing
//-----------------------------------------------------------------------
/**
* <p>Replaces a String with another String inside a larger String, once.</p>
*
* <p>A <code>null</code> reference passed to this method is a no-op.</p>
*
* <pre>
* StringUtils.replaceOnce(null, *, *) = null
* StringUtils.replaceOnce("", *, *) = ""
* StringUtils.replaceOnce("any", null, *) = "any"
* StringUtils.replaceOnce("any", *, null) = "any"
* StringUtils.replaceOnce("any", "", *) = "any"
* StringUtils.replaceOnce("aba", "a", null) = "aba"
* StringUtils.replaceOnce("aba", "a", "") = "ba"
* StringUtils.replaceOnce("aba", "a", "z") = "zba"
* </pre>
*
* @see #replace(String text, String repl, String with, int max)
* @param text text to search and replace in, may be null
* @param repl the String to search for, may be null
* @param with the String to replace with, may be null
* @return the text with any replacements processed,
* <code>null</code> if null String input
*/
public static String replaceOnce(String text, String repl, String with) {
return replace(text, repl, with, 1);
}
/**
* <p>Replaces all occurrences of a String within another String.</p>
*
* <p>A <code>null</code> reference passed to this method is a no-op.</p>
*
* <pre>
* StringUtils.replace(null, *, *) = null
* StringUtils.replace("", *, *) = ""
* StringUtils.replace("any", null, *) = "any"
* StringUtils.replace("any", *, null) = "any"
* StringUtils.replace("any", "", *) = "any"
* StringUtils.replace("aba", "a", null) = "aba"
* StringUtils.replace("aba", "a", "") = "b"
* StringUtils.replace("aba", "a", "z") = "zbz"
* </pre>
*
* @see #replace(String text, String repl, String with, int max)
* @param text text to search and replace in, may be null
* @param repl the String to search for, may be null
* @param with the String to replace with, may be null
* @return the text with any replacements processed,
* <code>null</code> if null String input
*/
public static String replace(String text, String repl, String with) {
return replace(text, repl, with, -1);
}
/**
* <p>Replaces a String with another String inside a larger String,
* for the first <code>max</code> values of the search String.</p>
*
* <p>A <code>null</code> reference passed to this method is a no-op.</p>
*
* <pre>
* StringUtils.replace(null, *, *, *) = null
* StringUtils.replace("", *, *, *) = ""
* StringUtils.replace("any", null, *, *) = "any"
* StringUtils.replace("any", *, null, *) = "any"
* StringUtils.replace("any", "", *, *) = "any"
* StringUtils.replace("any", *, *, 0) = "any"
* StringUtils.replace("abaa", "a", null, -1) = "abaa"
* StringUtils.replace("abaa", "a", "", -1) = "b"
* StringUtils.replace("abaa", "a", "z", 0) = "abaa"
* StringUtils.replace("abaa", "a", "z", 1) = "zbaa"
* StringUtils.replace("abaa", "a", "z", 2) = "zbza"
* StringUtils.replace("abaa", "a", "z", -1) = "zbzz"
* </pre>
*
* @param text text to search and replace in, may be null
* @param repl the String to search for, may be null
* @param with the String to replace with, may be null
* @param max maximum number of values to replace, or <code>-1</code> if no maximum
* @return the text with any replacements processed,
* <code>null</code> if null String input
*/
public static String replace(String text, String repl, String with, int max) {
if (text == null || isEmpty(repl) || with == null || max == 0) {
return text;
}
StringBuffer buf = new StringBuffer(text.length());
int start = 0, end = 0;
while ((end = text.indexOf(repl, start)) != -1) {
buf.append(text.substring(start, end)).append(with);
start = end + repl.length();
if (--max == 0) {
break;
}
}
buf.append(text.substring(start));
return buf.toString();
}
// Replace, character based
//-----------------------------------------------------------------------
/**
* <p>Replaces all occurrences of a character in a String with another.
* This is a null-safe version of {@link String#replace(char, char)}.</p>
*
* <p>A <code>null</code> string input returns <code>null</code>.
* An empty ("") string input returns an empty string.</p>
*
* <pre>
* StringUtils.replaceChars(null, *, *) = null
* StringUtils.replaceChars("", *, *) = ""
* StringUtils.replaceChars("abcba", 'b', 'y') = "aycya"
* StringUtils.replaceChars("abcba", 'z', 'y') = "abcba"
* </pre>
*
* @param str String to replace characters in, may be null
* @param searchChar the character to search for, may be null
* @param replaceChar the character to replace, may be null
* @return modified String, <code>null</code> if null string input
* @since 2.0
*/
public static String replaceChars(String str, char searchChar, char replaceChar) {
if (str == null) {
return null;
}
return str.replace(searchChar, replaceChar);
}
/**
* <p>Replaces multiple characters in a String in one go.
* This method can also be used to delete characters.</p>
*
* <p>For example:<br />
* <code>replaceChars("hello", "ho", "jy") = jelly</code>.</p>
*
* <p>A <code>null</code> string input returns <code>null</code>.
* An empty ("") string input returns an empty string.
* A null or empty set of search characters returns the input string.</p>
*
* <p>The length of the search characters should normally equal the length
* of the replace characters.
* If the search characters is longer, then the extra search characters
* are deleted.
* If the search characters is shorter, then the extra replace characters
* are ignored.</p>
*
* <pre>
* StringUtils.replaceChars(null, *, *) = null
* StringUtils.replaceChars("", *, *) = ""
* StringUtils.replaceChars("abc", null, *) = "abc"
* StringUtils.replaceChars("abc", "", *) = "abc"
* StringUtils.replaceChars("abc", "b", null) = "ac"
* StringUtils.replaceChars("abc", "b", "") = "ac"
* StringUtils.replaceChars("abcba", "bc", "yz") = "ayzya"
* StringUtils.replaceChars("abcba", "bc", "y") = "ayya"
* StringUtils.replaceChars("abcba", "bc", "yzx") = "ayzya"
* </pre>
*
* @param str String to replace characters in, may be null
* @param searchChars a set of characters to search for, may be null
* @param replaceChars a set of characters to replace, may be null
* @return modified String, <code>null</code> if null string input
* @since 2.0
*/
public static String replaceChars(String str, String searchChars, String replaceChars) {
if (isEmpty(str) || isEmpty(searchChars)) {
return str;
}
if (replaceChars == null) {
replaceChars = "";
}
boolean modified = false;
StringBuffer buf = new StringBuffer(str.length());
for (int i = 0; i < str.length(); i++) {
char ch = str.charAt(i);
int index = searchChars.indexOf(ch);
if (index >= 0) {
modified = true;
if (index < replaceChars.length()) {
buf.append(replaceChars.charAt(index));
}
} else {
buf.append(ch);
}
}
if (modified) {
return buf.toString();
} else {
return str;
}
}
// Overlay
//-----------------------------------------------------------------------
/**
* <p>Overlays part of a String with another String.</p>
*
* <pre>
* StringUtils.overlayString(null, *, *, *) = NullPointerException
* StringUtils.overlayString(*, null, *, *) = NullPointerException
* StringUtils.overlayString("", "abc", 0, 0) = "abc"
* StringUtils.overlayString("abcdef", null, 2, 4) = "abef"
* StringUtils.overlayString("abcdef", "", 2, 4) = "abef"
* StringUtils.overlayString("abcdef", "zzzz", 2, 4) = "abzzzzef"
* StringUtils.overlayString("abcdef", "zzzz", 4, 2) = "abcdzzzzcdef"
* StringUtils.overlayString("abcdef", "zzzz", -1, 4) = IndexOutOfBoundsException
* StringUtils.overlayString("abcdef", "zzzz", 2, 8) = IndexOutOfBoundsException
* </pre>
*
* @param text the String to do overlaying in, may be null
* @param overlay the String to overlay, may be null
* @param start the position to start overlaying at, must be valid
* @param end the position to stop overlaying before, must be valid
* @return overlayed String, <code>null</code> if null String input
* @throws NullPointerException if text or overlay is null
* @throws IndexOutOfBoundsException if either position is invalid
* @deprecated Use better named {@link #overlay(String, String, int, int)} instead.
* Method will be removed in Commons Lang 3.0.
*/
public static String overlayString(String text, String overlay, int start, int end) {
return new StringBuffer(start + overlay.length() + text.length() - end + 1)
.append(text.substring(0, start))
.append(overlay)
.append(text.substring(end))
.toString();
}
/**
* <p>Overlays part of a String with another String.</p>
*
* <p>A <code>null</code> string input returns <code>null</code>.
* A negative index is treated as zero.
* An index greater than the string length is treated as the string length.
* The start index is always the smaller of the two indices.</p>
*
* <pre>
* StringUtils.overlay(null, *, *, *) = null
* StringUtils.overlay("", "abc", 0, 0) = "abc"
* StringUtils.overlay("abcdef", null, 2, 4) = "abef"
* StringUtils.overlay("abcdef", "", 2, 4) = "abef"
* StringUtils.overlay("abcdef", "", 4, 2) = "abef"
* StringUtils.overlay("abcdef", "zzzz", 2, 4) = "abzzzzef"
* StringUtils.overlay("abcdef", "zzzz", 4, 2) = "abzzzzef"
* StringUtils.overlay("abcdef", "zzzz", -1, 4) = "zzzzef"
* StringUtils.overlay("abcdef", "zzzz", 2, 8) = "abzzzz"
* StringUtils.overlay("abcdef", "zzzz", -2, -3) = "zzzzabcdef"
* StringUtils.overlay("abcdef", "zzzz", 8, 10) = "abcdefzzzz"
* </pre>
*
* @param str the String to do overlaying in, may be null
* @param overlay the String to overlay, may be null
* @param start the position to start overlaying at
* @param end the position to stop overlaying before
* @return overlayed String, <code>null</code> if null String input
* @since 2.0
*/
public static String overlay(String str, String overlay, int start, int end) {
if (str == null) {
return null;
}
if (overlay == null) {
overlay = EMPTY;
}
int len = str.length();
if (start < 0) {
start = 0;
}
if (start > len) {
start = len;
}
if (end < 0) {
end = 0;
}
if (end > len) {
end = len;
}
if (start > end) {
int temp = start;
start = end;
end = temp;
}
return new StringBuffer(len + start - end + overlay.length() + 1)
.append(str.substring(0, start))
.append(overlay)
.append(str.substring(end))
.toString();
}
// Chomping
//-----------------------------------------------------------------------
/**
* <p>Removes one newline from end of a String if it's there,
* otherwise leave it alone. A newline is "<code>/n</code>",
* "<code>/r</code>", or "<code>/r/n</code>".</p>
*
* <p>NOTE: This method changed in 2.0.
* It now more closely matches Perl chomp.</p>
*
* <pre>
* StringUtils.chomp(null) = null
* StringUtils.chomp("") = ""
* StringUtils.chomp("abc /r") = "abc "
* StringUtils.chomp("abc/n") = "abc"
* StringUtils.chomp("abc/r/n") = "abc"
* StringUtils.chomp("abc/r/n/r/n") = "abc/r/n"
* StringUtils.chomp("abc/n/r") = "abc/n"
* StringUtils.chomp("abc/n/rabc") = "abc/n/rabc"
* StringUtils.chomp("/r") = ""
* StringUtils.chomp("/n") = ""
* StringUtils.chomp("/r/n") = ""
* </pre>
*
* @param str the String to chomp a newline from, may be null
* @return String without newline, <code>null</code> if null String input
*/
public static String chomp(String str) {
if (isEmpty(str)) {
return str;
}
if (str.length() == 1) {
char ch = str.charAt(0);
if (ch == '/r' || ch == '/n') {
return EMPTY;
} else {
return str;
}
}
int lastIdx = str.length() - 1;
char last = str.charAt(lastIdx);
if (last == '/n') {
if (str.charAt(lastIdx - 1) == '/r') {
lastIdx--;
}
} else if (last == '/r') {
// why is this block empty?
// just to skip incrementing the index?
} else {
lastIdx++;
}
return str.substring(0, lastIdx);
}
/**
* <p>Removes <code>separator</code> from the end of
* <code>str</code> if it's there, otherwise leave it alone.</p>
*
* <p>NOTE: This method changed in version 2.0.
* It now more closely matches Perl chomp.
* For the previous behavior, use {@link #substringBeforeLast(String, String)}.
* This method uses {@link String#endsWith(String)}.</p>
*
* <pre>
* StringUtils.chomp(null, *) = null
* StringUtils.chomp("", *) = ""
* StringUtils.chomp("foobar", "bar") = "foo"
* StringUtils.chomp("foobar", "baz") = "foobar"
* StringUtils.chomp("foo", "foo") = ""
* StringUtils.chomp("foo ", "foo") = "foo "
* StringUtils.chomp(" foo", "foo") = " "
* StringUtils.chomp("foo", "foooo") = "foo"
* StringUtils.chomp("foo", "") = "foo"
* StringUtils.chomp("foo", null) = "foo"
* </pre>
*
* @param str the String to chomp from, may be null
* @param separator separator String, may be null
* @return String without trailing separator, <code>null</code> if null String input
*/
public static String chomp(String str, String separator) {
if (isEmpty(str) || separator == null) {
return str;
}
if (str.endsWith(separator)) {
return str.substring(0, str.length() - separator.length());
}
return str;
}
/**
* <p>Remove any "/n" if and only if it is at the end
* of the supplied String.</p>
*
* @param str the String to chomp from, must not be null
* @return String without chomped ending
* @throws NullPointerException if str is <code>null</code>
* @deprecated Use {@link #chomp(String)} instead.
* Method will be removed in Commons Lang 3.0.
*/
public static String chompLast(String str) {
return chompLast(str, "/n");
}
/**
* <p>Remove a value if and only if the String ends with that value.</p>
*
* @param str the String to chomp from, must not be null
* @param sep the String to chomp, must not be null
* @return String without chomped ending
* @throws NullPointerException if str or sep is <code>null</code>
* @deprecated Use {@link #chomp(String,String)} instead.
* Method will be removed in Commons Lang 3.0.
*/
public static String chompLast(String str, String sep) {
if (str.length() == 0) {
return str;
}
String sub = str.substring(str.length() - sep.length());
if (sep.equals(sub)) {
return str.substring(0, str.length() - sep.length());
} else {
return str;
}
}
/**
* <p>Remove everything and return the last value of a supplied String, and
* everything after it from a String.</p>
*
* @param str the String to chomp from, must not be null
* @param sep the String to chomp, must not be null
* @return String chomped
* @throws NullPointerException if str or sep is <code>null</code>
* @deprecated Use {@link #substringAfterLast(String, String)} instead
* (although this doesn't include the separator)
* Method will be removed in Commons Lang 3.0.
*/
public static String getChomp(String str, String sep) {
int idx = str.lastIndexOf(sep);
if (idx == str.length() - sep.length()) {
return sep;
} else if (idx != -1) {
return str.substring(idx);
} else {
return EMPTY;
}
}
/**
* <p>Remove the first value of a supplied String, and everything before it
* from a String.</p>
*
* @param str the String to chomp from, must not be null
* @param sep the String to chomp, must not be null
* @return String without chomped beginning
* @throws NullPointerException if str or sep is <code>null</code>
* @deprecated Use {@link #substringAfter(String,String)} instead.
* Method will be removed in Commons Lang 3.0.
*/
public static String prechomp(String str, String sep) {
int idx = str.indexOf(sep);
if (idx != -1) {
return str.substring(idx + sep.length());
} else {
return str;
}
}
/**
* <p>Remove and return everything before the first value of a
* supplied String from another String.</p>
*
* @param str the String to chomp from, must not be null
* @param sep the String to chomp, must not be null
* @return String prechomped
* @throws NullPointerException if str or sep is <code>null</code>
* @deprecated Use {@link #substringBefore(String,String)} instead
* (although this doesn't include the separator).
* Method will be removed in Commons Lang 3.0.
*/
public static String getPrechomp(String str, String sep) {
int idx = str.indexOf(sep);
if (idx != -1) {
return str.substring(0, idx + sep.length());
} else {
return EMPTY;
}
}
// Chopping
//-----------------------------------------------------------------------
/**
* <p>Remove the last character from a String.</p>
*
* <p>If the String ends in <code>/r/n</code>, then remove both
* of them.</p>
*
* <pre>
* StringUtils.chop(null) = null
* StringUtils.chop("") = ""
* StringUtils.chop("abc /r") = "abc "
* StringUtils.chop("abc/n") = "abc"
* StringUtils.chop("abc/r/n") = "abc"
* StringUtils.chop("abc") = "ab"
* StringUtils.chop("abc/nabc") = "abc/nab"
* StringUtils.chop("a") = ""
* StringUtils.chop("/r") = ""
* StringUtils.chop("/n") = ""
* StringUtils.chop("/r/n") = ""
* </pre>
*
* @param str the String to chop last character from, may be null
* @return String without last character, <code>null</code> if null String input
*/
public static String chop(String str) {
if (str == null) {
return null;
}
int strLen = str.length();
if (strLen < 2) {
return EMPTY;
}
int lastIdx = strLen - 1;
String ret = str.substring(0, lastIdx);
char last = str.charAt(lastIdx);
if (last == '/n') {
if (ret.charAt(lastIdx - 1) == '/r') {
return ret.substring(0, lastIdx - 1);
}
}
return ret;
}
/**
* <p>Removes <code>/n</code> from end of a String if it's there.
* If a <code>/r</code> precedes it, then remove that too.</p>
*
* @param str the String to chop a newline from, must not be null
* @return String without newline
* @throws NullPointerException if str is <code>null</code>
* @deprecated Use {@link #chomp(String)} instead.
* Method will be removed in Commons Lang 3.0.
*/
public static String chopNewline(String str) {
int lastIdx = str.length() - 1;
if (lastIdx <= 0) {
return EMPTY;
}
char last = str.charAt(lastIdx);
if (last == '/n') {
if (str.charAt(lastIdx - 1) == '/r') {
lastIdx--;
}
} else {
lastIdx++;
}
return str.substring(0, lastIdx);
}
// Conversion
//-----------------------------------------------------------------------
/**
* <p>Escapes any values it finds into their String form.</p>
*
* <p>So a tab becomes the characters <code>'//'</code> and
* <code>'t'</code>.</p>
*
* <p>As of Lang 2.0, this calls {@link StringEscapeUtils#escapeJava(String)}
* behind the scenes.
* </p>
* @see StringEscapeUtils#escapeJava(java.lang.String)
* @param str String to escape values in
* @return String with escaped values
* @throws NullPointerException if str is <code>null</code>
* @deprecated Use {@link StringEscapeUtils#escapeJava(String)}
* This method will be removed in Commons Lang 3.0
*/
public static String escape(String str) {
return StringEscapeUtils.escapeJava(str);
}
// Padding
//-----------------------------------------------------------------------
/**
* <p>Repeat a String <code>repeat</code> times to form a
* new String.</p>
*
* <pre>
* StringUtils.repeat(null, 2) = null
* StringUtils.repeat("", 0) = ""
* StringUtils.repeat("", 2) = ""
* StringUtils.repeat("a", 3) = "aaa"
* StringUtils.repeat("ab", 2) = "abab"
* StringUtils.repeat("a", -2) = ""
* </pre>
*
* @param str the String to repeat, may be null
* @param repeat number of times to repeat str, negative treated as zero
* @return a new String consisting of the original String repeated,
* <code>null</code> if null String input
*/
public static String repeat(String str, int repeat) {
// Performance tuned for 2.0 (JDK1.4)
if (str == null) {
return null;
}
if (repeat <= 0) {
return EMPTY;
}
int inputLength = str.length();
if (repeat == 1 || inputLength == 0) {
return str;
}
if (inputLength == 1 && repeat <= PAD_LIMIT) {
return padding(repeat, str.charAt(0));
}
int outputLength = inputLength * repeat;
switch (inputLength) {
case 1 :
char ch = str.charAt(0);
char[] output1 = new char[outputLength];
for (int i = repeat - 1; i >= 0; i--) {
output1[i] = ch;
}
return new String(output1);
case 2 :
char ch0 = str.charAt(0);
char ch1 = str.charAt(1);
char[] output2 = new char[outputLength];
for (int i = repeat * 2 - 2; i >= 0; i--, i--) {
output2[i] = ch0;
output2[i + 1] = ch1;
}
return new String(output2);
default :
StringBuffer buf = new StringBuffer(outputLength);
for (int i = 0; i < repeat; i++) {
buf.append(str);
}
return buf.toString();
}
}
/**
* <p>Returns padding using the specified delimiter repeated
* to a given length.</p>
*
* <pre>
* StringUtils.padding(0, 'e') = ""
* StringUtils.padding(3, 'e') = "eee"
* StringUtils.padding(-2, 'e') = IndexOutOfBoundsException
* </pre>
*
* @param repeat number of times to repeat delim
* @param padChar character to repeat
* @return String with repeated character
* @throws IndexOutOfBoundsException if <code>repeat < 0</code>
*/
private static String padding(int repeat, char padChar) {
// be careful of synchronization in this method
// we are assuming that get and set from an array index is atomic
String pad = PADDING[padChar];
if (pad == null) {
pad = String.valueOf(padChar);
}
while (pad.length() < repeat) {
pad = pad.concat(pad);
}
PADDING[padChar] = pad;
return pad.substring(0, repeat);
}
/**
* <p>Right pad a String with spaces (' ').</p>
*
* <p>The String is padded to the size of <code>size</code>.</p>
*
* <pre>
* StringUtils.rightPad(null, *) = null
* StringUtils.rightPad("", 3) = " "
* StringUtils.rightPad("bat", 3) = "bat"
* StringUtils.rightPad("bat", 5) = "bat "
* StringUtils.rightPad("bat", 1) = "bat"
* StringUtils.rightPad("bat", -1) = "bat"
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @return right padded String or original String if no padding is necessary,
* <code>null</code> if null String input
*/
public static String rightPad(String str, int size) {
return rightPad(str, size, ' ');
}
/**
* <p>Right pad a String with a specified character.</p>
*
* <p>The String is padded to the size of <code>size</code>.</p>
*
* <pre>
* StringUtils.rightPad(null, *, *) = null
* StringUtils.rightPad("", 3, 'z') = "zzz"
* StringUtils.rightPad("bat", 3, 'z') = "bat"
* StringUtils.rightPad("bat", 5, 'z') = "batzz"
* StringUtils.rightPad("bat", 1, 'z') = "bat"
* StringUtils.rightPad("bat", -1, 'z') = "bat"
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padChar the character to pad with
* @return right padded String or original String if no padding is necessary,
* <code>null</code> if null String input
* @since 2.0
*/
public static String rightPad(String str, int size, char padChar) {
if (str == null) {
return null;
}
int pads = size - str.length();
if (pads <= 0) {
return str; // returns original String when possible
}
if (pads > PAD_LIMIT) {
return rightPad(str, size, String.valueOf(padChar));
}
return str.concat(padding(pads, padChar));
}
/**
* <p>Right pad a String with a specified String.</p>
*
* <p>The String is padded to the size of <code>size</code>.</p>
*
* <pre>
* StringUtils.rightPad(null, *, *) = null
* StringUtils.rightPad("", 3, "z") = "zzz"
* StringUtils.rightPad("bat", 3, "yz") = "bat"
* StringUtils.rightPad("bat", 5, "yz") = "batyz"
* StringUtils.rightPad("bat", 8, "yz") = "batyzyzy"
* StringUtils.rightPad("bat", 1, "yz") = "bat"
* StringUtils.rightPad("bat", -1, "yz") = "bat"
* StringUtils.rightPad("bat", 5, null) = "bat "
* StringUtils.rightPad("bat", 5, "") = "bat "
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padStr the String to pad with, null or empty treated as single space
* @return right padded String or original String if no padding is necessary,
* <code>null</code> if null String input
*/
public static String rightPad(String str, int size, String padStr) {
if (str == null) {
return null;
}
if (isEmpty(padStr)) {
padStr = " ";
}
int padLen = padStr.length();
int strLen = str.length();
int pads = size - strLen;
if (pads <= 0) {
return str; // returns original String when possible
}
if (padLen == 1 && pads <= PAD_LIMIT) {
return rightPad(str, size, padStr.charAt(0));
}
if (pads == padLen) {
return str.concat(padStr);
} else if (pads < padLen) {
return str.concat(padStr.substring(0, pads));
} else {
char[] padding = new char[pads];
char[] padChars = padStr.toCharArray();
for (int i = 0; i < pads; i++) {
padding[i] = padChars[i % padLen];
}
return str.concat(new String(padding));
}
}
/**
* <p>Left pad a String with spaces (' ').</p>
*
* <p>The String is padded to the size of <code>size<code>.</p>
*
* <pre>
* StringUtils.leftPad(null, *) = null
* StringUtils.leftPad("", 3) = " "
* StringUtils.leftPad("bat", 3) = "bat"
* StringUtils.leftPad("bat", 5) = " bat"
* StringUtils.leftPad("bat", 1) = "bat"
* StringUtils.leftPad("bat", -1) = "bat"
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @return left padded String or original String if no padding is necessary,
* <code>null</code> if null String input
*/
public static String leftPad(String str, int size) {
return leftPad(str, size, ' ');
}
/**
* <p>Left pad a String with a specified character.</p>
*
* <p>Pad to a size of <code>size</code>.</p>
*
* <pre>
* StringUtils.leftPad(null, *, *) = null
* StringUtils.leftPad("", 3, 'z') = "zzz"
* StringUtils.leftPad("bat", 3, 'z') = "bat"
* StringUtils.leftPad("bat", 5, 'z') = "zzbat"
* StringUtils.leftPad("bat", 1, 'z') = "bat"
* StringUtils.leftPad("bat", -1, 'z') = "bat"
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padChar the character to pad with
* @return left padded String or original String if no padding is necessary,
* <code>null</code> if null String input
* @since 2.0
*/
public static String leftPad(String str, int size, char padChar) {
if (str == null) {
return null;
}
int pads = size - str.length();
if (pads <= 0) {
return str; // returns original String when possible
}
if (pads > PAD_LIMIT) {
return leftPad(str, size, String.valueOf(padChar));
}
return padding(pads, padChar).concat(str);
}
/**
* <p>Left pad a String with a specified String.</p>
*
* <p>Pad to a size of <code>size</code>.</p>
*
* <pre>
* StringUtils.leftPad(null, *, *) = null
* StringUtils.leftPad("", 3, "z") = "zzz"
* StringUtils.leftPad("bat", 3, "yz") = "bat"
* StringUtils.leftPad("bat", 5, "yz") = "yzbat"
* StringUtils.leftPad("bat", 8, "yz") = "yzyzybat"
* StringUtils.leftPad("bat", 1, "yz") = "bat"
* StringUtils.leftPad("bat", -1, "yz") = "bat"
* StringUtils.leftPad("bat", 5, null) = " bat"
* StringUtils.leftPad("bat", 5, "") = " bat"
* </pre>
*
* @param str the String to pad out, may be null
* @param size the size to pad to
* @param padStr the String to pad with, null or empty treated as single space
* @return left padded String or original String if no padding is necessary,
* <code>null</code> if null String input
*/
public static String leftPad(String str, int size, String padStr) {
if (str == null) {
return null;
}
if (isEmpty(padStr)) {
padStr = " ";
}
int padLen = padStr.length();
int strLen = str.length();
int pads = size - strLen;
if (pads <= 0) {
return str; // returns original String when possible
}
if (padLen == 1 && pads <= PAD_LIMIT) {
return leftPad(str, size, padStr.charAt(0));
}
if (pads == padLen) {
return padStr.concat(str);
} else if (pads < padLen) {
return padStr.substring(0, pads).concat(str);
} else {
char[] padding = new char[pads];
char[] padChars = padStr.toCharArray();
for (int i = 0; i < pads; i++) {
padding[i] = padChars[i % padLen];
}
return new String(padding).concat(str);
}
}
// Centering
//-----------------------------------------------------------------------
/**
* <p>Centers a String in a larger String of size <code>size</code>
* using the space character (' ').<p>
*
* <p>If the size is less than the String length, the String is returned.
* A <code>null</code> String returns <code>null</code>.
* A negative size is treated as zero.</p>
*
* <p>Equivalent to <code>center(str, size, " ")</code>.</p>
*
* <pre>
* StringUtils.center(null, *) = null
* StringUtils.center("", 4) = " "
* StringUtils.center("ab", -1) = "ab"
* StringUtils.center("ab", 4) = " ab "
* StringUtils.center("abcd", 2) = "abcd"
* StringUtils.center("a", 4) = " a "
* </pre>
*
* @param str the String to center, may be null
* @param size the int size of new String, negative treated as zero
* @return centered String, <code>null</code> if null String input
*/
public static String center(String str, int size) {
return center(str, size, ' ');
}
/**
* <p>Centers a String in a larger String of size <code>size</code>.
* Uses a supplied character as the value to pad the String with.</p>
*
* <p>If the size is less than the String length, the String is returned.
* A <code>null</code> String returns <code>null</code>.
* A negative size is treated as zero.</p>
*
* <pre>
* StringUtils.center(null, *, *) = null
* StringUtils.center("", 4, ' ') = " "
* StringUtils.center("ab", -1, ' ') = "ab"
* StringUtils.center("ab", 4, ' ') = " ab"
* StringUtils.center("abcd", 2, ' ') = "abcd"
* StringUtils.center("a", 4, ' ') = " a "
* StringUtils.center("a", 4, 'y') = "yayy"
* </pre>
*
* @param str the String to center, may be null
* @param size the int size of new String, negative treated as zero
* @param padChar the character to pad the new String with
* @return centered String, <code>null</code> if null String input
* @since 2.0
*/
public static String center(String str, int size, char padChar) {
if (str == null || size <= 0) {
return str;
}
int strLen = str.length();
int pads = size - strLen;
if (pads <= 0) {
return str;
}
str = leftPad(str, strLen + pads / 2, padChar);
str = rightPad(str, size, padChar);
return str;
}
/**
* <p>Centers a String in a larger String of size <code>size</code>.
* Uses a supplied String as the value to pad the String with.</p>
*
* <p>If the size is less than the String length, the String is returned.
* A <code>null</code> String returns <code>null</code>.
* A negative size is treated as zero.</p>
*
* <pre>
* StringUtils.center(null, *, *) = null
* StringUtils.center("", 4, " ") = " "
* StringUtils.center("ab", -1, " ") = "ab"
* StringUtils.center("ab", 4, " ") = " ab"
* StringUtils.center("abcd", 2, " ") = "abcd"
* StringUtils.center("a", 4, " ") = " a "
* StringUtils.center("a", 4, "yz") = "yayz"
* StringUtils.center("abc", 7, null) = " abc "
* StringUtils.center("abc", 7, "") = " abc "
* </pre>
*
* @param str the String to center, may be null
* @param size the int size of new String, negative treated as zero
* @param padStr the String to pad the new String with, must not be null or empty
* @return centered String, <code>null</code> if null String input
* @throws IllegalArgumentException if padStr is <code>null</code> or empty
*/
public static String center(String str, int size, String padStr) {
if (str == null || size <= 0) {
return str;
}
if (isEmpty(padStr)) {
padStr = " ";
}
int strLen = str.length();
int pads = size - strLen;
if (pads <= 0) {
return str;
}
str = leftPad(str, strLen + pads / 2, padStr);
str = rightPad(str, size, padStr);
return str;
}
// Case conversion
//-----------------------------------------------------------------------
/**
* <p>Converts a String to upper case as per {@link String#toUpperCase()}.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.upperCase(null) = null
* StringUtils.upperCase("") = ""
* StringUtils.upperCase("aBc") = "ABC"
* </pre>
*
* @param str the String to upper case, may be null
* @return the upper cased String, <code>null</code> if null String input
*/
public static String upperCase(String str) {
if (str == null) {
return null;
}
return str.toUpperCase();
}
/**
* <p>Converts a String to lower case as per {@link String#toLowerCase()}.</p>
*
* <p>A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.lowerCase(null) = null
* StringUtils.lowerCase("") = ""
* StringUtils.lowerCase("aBc") = "abc"
* </pre>
*
* @param str the String to lower case, may be null
* @return the lower cased String, <code>null</code> if null String input
*/
public static String lowerCase(String str) {
if (str == null) {
return null;
}
return str.toLowerCase();
}
/**
* <p>Capitalizes a String changing the first letter to title case as
* per {@link Character#toTitleCase(char)}. No other letters are changed.</p>
*
* <p>For a word based algorithm, see {@link WordUtils#capitalize(String)}.
* A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.capitalize(null) = null
* StringUtils.capitalize("") = ""
* StringUtils.capitalize("cat") = "Cat"
* StringUtils.capitalize("cAt") = "CAt"
* </pre>
*
* @param str the String to capitalize, may be null
* @return the capitalized String, <code>null</code> if null String input
* @see WordUtils#capitalize(String)
* @see #uncapitalize(String)
* @since 2.0
*/
public static String capitalize(String str) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return str;
}
return new StringBuffer(strLen)
.append(Character.toTitleCase(str.charAt(0)))
.append(str.substring(1))
.toString();
}
/**
* <p>Capitalizes a String changing the first letter to title case as
* per {@link Character#toTitleCase(char)}. No other letters are changed.</p>
*
* @param str the String to capitalize, may be null
* @return the capitalized String, <code>null</code> if null String input
* @deprecated Use the standardly named {@link #capitalize(String)}.
* Method will be removed in Commons Lang 3.0.
*/
public static String capitalise(String str) {
return capitalize(str);
}
/**
* <p>Uncapitalizes a String changing the first letter to title case as
* per {@link Character#toLowerCase(char)}. No other letters are changed.</p>
*
* <p>For a word based algorithm, see {@link WordUtils#uncapitalize(String)}.
* A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.uncapitalize(null) = null
* StringUtils.uncapitalize("") = ""
* StringUtils.uncapitalize("Cat") = "cat"
* StringUtils.uncapitalize("CAT") = "cAT"
* </pre>
*
* @param str the String to uncapitalize, may be null
* @return the uncapitalized String, <code>null</code> if null String input
* @see WordUtils#uncapitalize(String)
* @see #capitalize(String)
* @since 2.0
*/
public static String uncapitalize(String str) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return str;
}
return new StringBuffer(strLen)
.append(Character.toLowerCase(str.charAt(0)))
.append(str.substring(1))
.toString();
}
/**
* <p>Uncapitalizes a String changing the first letter to title case as
* per {@link Character#toLowerCase(char)}. No other letters are changed.</p>
*
* @param str the String to uncapitalize, may be null
* @return the uncapitalized String, <code>null</code> if null String input
* @deprecated Use the standardly named {@link #uncapitalize(String)}.
* Method will be removed in Commons Lang 3.0.
*/
public static String uncapitalise(String str) {
return uncapitalize(str);
}
/**
* <p>Swaps the case of a String changing upper and title case to
* lower case, and lower case to upper case.</p>
*
* <ul>
* <li>Upper case character converts to Lower case</li>
* <li>Title case character converts to Lower case</li>
* <li>Lower case character converts to Upper case</li>
* </ul>
*
* <p>For a word based algorithm, see {@link WordUtils#swapCase(String)}.
* A <code>null</code> input String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.swapCase(null) = null
* StringUtils.swapCase("") = ""
* StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone"
* </pre>
*
* <p>NOTE: This method changed in Lang version 2.0.
* It no longer performs a word based algorithm.
* If you only use ASCII, you will notice no change.
* That functionality is available in WordUtils.</p>
*
* @param str the String to swap case, may be null
* @return the changed String, <code>null</code> if null String input
*/
public static String swapCase(String str) {
int strLen;
if (str == null || (strLen = str.length()) == 0) {
return str;
}
StringBuffer buffer = new StringBuffer(strLen);
char ch = 0;
for (int i = 0; i < strLen; i++) {
ch = str.charAt(i);
if (Character.isUpperCase(ch)) {
ch = Character.toLowerCase(ch);
} else if (Character.isTitleCase(ch)) {
ch = Character.toLowerCase(ch);
} else if (Character.isLowerCase(ch)) {
ch = Character.toUpperCase(ch);
}
buffer.append(ch);
}
return buffer.toString();
}
/**
* <p>Capitalizes all the whitespace separated words in a String.
* Only the first letter of each word is changed.</p>
*
* <p>Whitespace is defined by {@link Character#isWhitespace(char)}.
* A <code>null</code> input String returns <code>null</code>.</p>
*
* @param str the String to capitalize, may be null
* @return capitalized String, <code>null</code> if null String input
* @deprecated Use the relocated {@link WordUtils#capitalize(String)}.
* Method will be removed in Commons Lang 3.0.
*/
public static String capitaliseAllWords(String str) {
return WordUtils.capitalize(str);
}
// Count matches
//-----------------------------------------------------------------------
/**
* <p>Counts how many times the substring appears in the larger String.</p>
*
* <p>A <code>null</code> or empty ("") String input returns <code>0</code>.</p>
*
* <pre>
* StringUtils.countMatches(null, *) = 0
* StringUtils.countMatches("", *) = 0
* StringUtils.countMatches("abba", null) = 0
* StringUtils.countMatches("abba", "") = 0
* StringUtils.countMatches("abba", "a") = 2
* StringUtils.countMatches("abba", "ab") = 1
* StringUtils.countMatches("abba", "xxx") = 0
* </pre>
*
* @param str the String to check, may be null
* @param sub the substring to count, may be null
* @return the number of occurrences, 0 if either String is <code>null</code>
*/
public static int countMatches(String str, String sub) {
if (isEmpty(str) || isEmpty(sub)) {
return 0;
}
int count = 0;
int idx = 0;
while ((idx = str.indexOf(sub, idx)) != -1) {
count++;
idx += sub.length();
}
return count;
}
// Character Tests
//-----------------------------------------------------------------------
/**
* <p>Checks if the String contains only unicode letters.</p>
*
* <p><code>null</code> will return <code>false</code>.
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isAlpha(null) = false
* StringUtils.isAlpha("") = true
* StringUtils.isAlpha(" ") = false
* StringUtils.isAlpha("abc") = true
* StringUtils.isAlpha("ab2c") = false
* StringUtils.isAlpha("ab-c") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if only contains letters, and is non-null
*/
public static boolean isAlpha(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if (Character.isLetter(str.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* <p>Checks if the String contains only unicode letters and
* space (' ').</p>
*
* <p><code>null</code> will return <code>false</code>
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isAlphaSpace(null) = false
* StringUtils.isAlphaSpace("") = true
* StringUtils.isAlphaSpace(" ") = true
* StringUtils.isAlphaSpace("abc") = true
* StringUtils.isAlphaSpace("ab c") = true
* StringUtils.isAlphaSpace("ab2c") = false
* StringUtils.isAlphaSpace("ab-c") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if only contains letters and space,
* and is non-null
*/
public static boolean isAlphaSpace(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if ((Character.isLetter(str.charAt(i)) == false) && (str.charAt(i) != ' ')) {
return false;
}
}
return true;
}
/**
* <p>Checks if the String contains only unicode letters or digits.</p>
*
* <p><code>null</code> will return <code>false</code>.
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isAlphanumeric(null) = false
* StringUtils.isAlphanumeric("") = true
* StringUtils.isAlphanumeric(" ") = false
* StringUtils.isAlphanumeric("abc") = true
* StringUtils.isAlphanumeric("ab c") = false
* StringUtils.isAlphanumeric("ab2c") = true
* StringUtils.isAlphanumeric("ab-c") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if only contains letters or digits,
* and is non-null
*/
public static boolean isAlphanumeric(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if (Character.isLetterOrDigit(str.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* <p>Checks if the String contains only unicode letters, digits
* or space (<code>' '</code>).</p>
*
* <p><code>null</code> will return <code>false</code>.
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isAlphanumeric(null) = false
* StringUtils.isAlphanumeric("") = true
* StringUtils.isAlphanumeric(" ") = true
* StringUtils.isAlphanumeric("abc") = true
* StringUtils.isAlphanumeric("ab c") = true
* StringUtils.isAlphanumeric("ab2c") = true
* StringUtils.isAlphanumeric("ab-c") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if only contains letters, digits or space,
* and is non-null
*/
public static boolean isAlphanumericSpace(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if ((Character.isLetterOrDigit(str.charAt(i)) == false) && (str.charAt(i) != ' ')) {
return false;
}
}
return true;
}
/**
* <p>Checks if the string contains only ASCII printable characters.</p>
*
* <p><code>null</code> will return <code>false</code>.
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isAsciiPrintable(null) = false
* StringUtils.isAsciiPrintable("") = true
* StringUtils.isAsciiPrintable(" ") = true
* StringUtils.isAsciiPrintable("Ceki") = true
* StringUtils.isAsciiPrintable("ab2c") = true
* StringUtils.isAsciiPrintable("!ab-c~") = true
* StringUtils.isAsciiPrintable("/u0020") = true
* StringUtils.isAsciiPrintable("/u0021") = true
* StringUtils.isAsciiPrintable("/u007e") = true
* StringUtils.isAsciiPrintable("/u007f") = false
* StringUtils.isAsciiPrintable("Ceki G/u00fclc/u00fc") = false
* </pre>
*
* @param str the string to check, may be null
* @return <code>true</code> if every character is in the range
* 32 thru 126
* @since 2.1
*/
public static boolean isAsciiPrintable(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if (CharUtils.isAsciiPrintable(str.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* <p>Checks if the String contains only unicode digits.
* A decimal point is not a unicode digit and returns false.</p>
*
* <p><code>null</code> will return <code>false</code>.
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isNumeric(null) = false
* StringUtils.isNumeric("") = true
* StringUtils.isNumeric(" ") = false
* StringUtils.isNumeric("123") = true
* StringUtils.isNumeric("12 3") = false
* StringUtils.isNumeric("ab2c") = false
* StringUtils.isNumeric("12-3") = false
* StringUtils.isNumeric("12.3") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if only contains digits, and is non-null
*/
public static boolean isNumeric(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if (Character.isDigit(str.charAt(i)) == false) {
return false;
}
}
return true;
}
/**
* <p>Checks if the String contains only unicode digits or space
* (<code>' '</code>).
* A decimal point is not a unicode digit and returns false.</p>
*
* <p><code>null</code> will return <code>false</code>.
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isNumeric(null) = false
* StringUtils.isNumeric("") = true
* StringUtils.isNumeric(" ") = true
* StringUtils.isNumeric("123") = true
* StringUtils.isNumeric("12 3") = true
* StringUtils.isNumeric("ab2c") = false
* StringUtils.isNumeric("12-3") = false
* StringUtils.isNumeric("12.3") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if only contains digits or space,
* and is non-null
*/
public static boolean isNumericSpace(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if ((Character.isDigit(str.charAt(i)) == false) && (str.charAt(i) != ' ')) {
return false;
}
}
return true;
}
/**
* <p>Checks if the String contains only whitespace.</p>
*
* <p><code>null</code> will return <code>false</code>.
* An empty String ("") will return <code>true</code>.</p>
*
* <pre>
* StringUtils.isWhitespace(null) = false
* StringUtils.isWhitespace("") = true
* StringUtils.isWhitespace(" ") = true
* StringUtils.isWhitespace("abc") = false
* StringUtils.isWhitespace("ab2c") = false
* StringUtils.isWhitespace("ab-c") = false
* </pre>
*
* @param str the String to check, may be null
* @return <code>true</code> if only contains whitespace, and is non-null
* @since 2.0
*/
public static boolean isWhitespace(String str) {
if (str == null) {
return false;
}
int sz = str.length();
for (int i = 0; i < sz; i++) {
if ((Character.isWhitespace(str.charAt(i)) == false)) {
return false;
}
}
return true;
}
// Defaults
//-----------------------------------------------------------------------
/**
* <p>Returns either the passed in String,
* or if the String is <code>null</code>, an empty String ("").</p>
*
* <pre>
* StringUtils.defaultString(null) = ""
* StringUtils.defaultString("") = ""
* StringUtils.defaultString("bat") = "bat"
* </pre>
*
* @see ObjectUtils#toString(Object)
* @see String#valueOf(Object)
* @param str the String to check, may be null
* @return the passed in String, or the empty String if it
* was <code>null</code>
*/
public static String defaultString(String str) {
return str == null ? EMPTY : str;
}
/**
* <p>Returns either the passed in String, or if the String is
* <code>null</code>, the value of <code>defaultStr</code>.</p>
*
* <pre>
* StringUtils.defaultString(null, "NULL") = "NULL"
* StringUtils.defaultString("", "NULL") = ""
* StringUtils.defaultString("bat", "NULL") = "bat"
* </pre>
*
* @see ObjectUtils#toString(Object,String)
* @see String#valueOf(Object)
* @param str the String to check, may be null
* @param defaultStr the default String to return
* if the input is <code>null</code>, may be null
* @return the passed in String, or the default if it was <code>null</code>
*/
public static String defaultString(String str, String defaultStr) {
return str == null ? defaultStr : str;
}
/**
* <p>Returns either the passed in String, or if the String is
* empty or <code>null</code>, the value of <code>defaultStr</code>.</p>
*
* <pre>
* StringUtils.defaultIfEmpty(null, "NULL") = "NULL"
* StringUtils.defaultIfEmpty("", "NULL") = "NULL"
* StringUtils.defaultIfEmpty("bat", "NULL") = "bat"
* </pre>
*
* @see StringUtils#defaultString(String, String)
* @param str the String to check, may be null
* @param defaultStr the default String to return
* if the input is empty ("") or <code>null</code>, may be null
* @return the passed in String, or the default
*/
public static String defaultIfEmpty(String str, String defaultStr) {
return StringUtils.isEmpty(str) ? defaultStr : str;
}
// Reversing
//-----------------------------------------------------------------------
/**
* <p>Reverses a String as per {@link StringBuffer#reverse()}.</p>
*
* <p>A <code>null</code> String returns <code>null</code>.</p>
*
* <pre>
* StringUtils.reverse(null) = null
* StringUtils.reverse("") = ""
* StringUtils.reverse("bat") = "tab"
* </pre>
*
* @param str the String to reverse, may be null
* @return the reversed String, <code>null</code> if null String input
*/
public static String reverse(String str) {
if (str == null) {
return null;
}
return new StringBuffer(str).reverse().toString();
}
/**
* <p>Reverses a String that is delimited by a specific character.</p>
*
* <p>The Strings between the delimiters are not reversed.
* Thus java.lang.String becomes String.lang.java (if the delimiter
* is <code>'.'</code>).</p>
*
* <pre>
* StringUtils.reverseDelimited(null, *) = null
* StringUtils.reverseDelimited("", *) = ""
* StringUtils.reverseDelimited("a.b.c", 'x') = "a.b.c"
* StringUtils.reverseDelimited("a.b.c", ".") = "c.b.a"
* </pre>
*
* @param str the String to reverse, may be null
* @param separatorChar the separator character to use
* @return the reversed String, <code>null</code> if null String input
* @since 2.0
*/
public static String reverseDelimited(String str, char separatorChar) {
if (str == null) {
return null;
}
// could implement manually, but simple way is to reuse other,
// probably slower, methods.
String[] strs = split(str, separatorChar);
ArrayUtils.reverse(strs);
return join(strs, separatorChar);
}
/**
* <p>Reverses a String that is delimited by a specific character.</p>
*
* <p>The Strings between the delimiters are not reversed.
* Thus java.lang.String becomes String.lang.java (if the delimiter
* is <code>"."</code>).</p>
*
* <pre>
* StringUtils.reverseDelimitedString(null, *) = null
* StringUtils.reverseDelimitedString("",*) = ""
* StringUtils.reverseDelimitedString("a.b.c", null) = "a.b.c"
* StringUtils.reverseDelimitedString("a.b.c", ".") = "c.b.a"
* </pre>
*
* @param str the String to reverse, may be null
* @param separatorChars the separator characters to use, null treated as whitespace
* @return the reversed String, <code>null</code> if null String input
* @deprecated Use {@link #reverseDelimited(String, char)} instead.
* This method is broken as the join doesn't know which char to use.
* Method will be removed in Commons Lang 3.0.
*
*/
public static String reverseDelimitedString(String str, String separatorChars) {
if (str == null) {
return null;
}
// could implement manually, but simple way is to reuse other,
// probably slower, methods.
String[] strs = split(str, separatorChars);
ArrayUtils.reverse(strs);
if (separatorChars == null) {
return join(strs, ' ');
}
return join(strs, separatorChars);
}
// Abbreviating
//-----------------------------------------------------------------------
/**
* <p>Abbreviates a String using ellipses. This will turn
* "Now is the time for all good men" into "Now is the time for..."</p>
*
* <p>Specifically:
* <ul>
* <li>If <code>str</code> is less than <code>maxWidth</code> characters
* long, return it.</li>
* <li>Else abbreviate it to <code>(substring(str, 0, max-3) + "...")</code>.</li>
* <li>If <code>maxWidth</code> is less than <code>4</code>, throw an
* <code>IllegalArgumentException</code>.</li>
* <li>In no case will it return a String of length greater than
* <code>maxWidth</code>.</li>
* </ul>
* </p>
*
* <pre>
* StringUtils.abbreviate(null, *) = null
* StringUtils.abbreviate("", 4) = ""
* StringUtils.abbreviate("abcdefg", 6) = "abc..."
* StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
* StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
* StringUtils.abbreviate("abcdefg", 4) = "a..."
* StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
* </pre>
*
* @param str the String to check, may be null
* @param maxWidth maximum length of result String, must be at least 4
* @return abbreviated String, <code>null</code> if null String input
* @throws IllegalArgumentException if the width is too small
* @since 2.0
*/
public static String abbreviate(String str, int maxWidth) {
return abbreviate(str, 0, maxWidth);
}
/**
* <p>Abbreviates a String using ellipses. This will turn
* "Now is the time for all good men" into "...is the time for..."</p>
*
* <p>Works like <code>abbreviate(String, int)</code>, but allows you to specify
* a "left edge" offset. Note that this left edge is not necessarily going to
* be the leftmost character in the result, or the first character following the
* ellipses, but it will appear somewhere in the result.
*
* <p>In no case will it return a String of length greater than
* <code>maxWidth</code>.</p>
*
* <pre>
* StringUtils.abbreviate(null, *, *) = null
* StringUtils.abbreviate("", 0, 4) = ""
* StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..."
* StringUtils.abbreviate("abcdefghijklmno", 0, 10) = "abcdefg..."
* StringUtils.abbreviate("abcdefghijklmno", 1, 10) = "abcdefg..."
* StringUtils.abbreviate("abcdefghijklmno", 4, 10) = "abcdefg..."
* StringUtils.abbreviate("abcdefghijklmno", 5, 10) = "...fghi..."
* StringUtils.abbreviate("abcdefghijklmno", 6, 10) = "...ghij..."
* StringUtils.abbreviate("abcdefghijklmno", 8, 10) = "...ijklmno"
* StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno"
* StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno"
* StringUtils.abbreviate("abcdefghij", 0, 3) = IllegalArgumentException
* StringUtils.abbreviate("abcdefghij", 5, 6) = IllegalArgumentException
* </pre>
*
* @param str the String to check, may be null
* @param offset left edge of source String
* @param maxWidth maximum length of result String, must be at least 4
* @return abbreviated String, <code>null</code> if null String input
* @throws IllegalArgumentException if the width is too small
* @since 2.0
*/
public static String abbreviate(String str, int offset, int maxWidth) {
if (str == null) {
return null;
}
if (maxWidth < 4) {
throw new IllegalArgumentException("Minimum abbreviation width is 4");
}
if (str.length() <= maxWidth) {
return str;
}
if (offset > str.length()) {
offset = str.length();
}
if ((str.length() - offset) < (maxWidth - 3)) {
offset = str.length() - (maxWidth - 3);
}
if (offset <= 4) {
return str.substring(0, maxWidth - 3) + "...";
}
if (maxWidth < 7) {
throw new IllegalArgumentException("Minimum abbreviation width with offset is 7");
}
if ((offset + (maxWidth - 3)) < str.length()) {
return "..." + abbreviate(str.substring(offset), maxWidth - 3);
}
return "..." + str.substring(str.length() - (maxWidth - 3));
}
// Difference
//-----------------------------------------------------------------------
/**
* <p>Compares two Strings, and returns the portion where they differ.
* (More precisely, return the remainder of the second String,
* starting from where it's different from the first.)</p>
*
* <p>For example,
* <code>difference("i am a machine", "i am a robot") -> "robot"</code>.</p>
*
* <pre>
* StringUtils.difference(null, null) = null
* StringUtils.difference("", "") = ""
* StringUtils.difference("", "abc") = "abc"
* StringUtils.difference("abc", "") = ""
* StringUtils.difference("abc", "abc") = ""
* StringUtils.difference("ab", "abxyz") = "xyz"
* StringUtils.difference("abcde", "abxyz") = "xyz"
* StringUtils.difference("abcde", "xyz") = "xyz"
* </pre>
*
* @param str1 the first String, may be null
* @param str2 the second String, may be null
* @return the portion of str2 where it differs from str1; returns the
* empty String if they are equal
* @since 2.0
*/
public static String difference(String str1, String str2) {
if (str1 == null) {
return str2;
}
if (str2 == null) {
return str1;
}
int at = indexOfDifference(str1, str2);
if (at == -1) {
return EMPTY;
}
return str2.substring(at);
}
/**
* <p>Compares two Strings, and returns the index at which the
* Strings begin to differ.</p>
*
* <p>For example,
* <code>indexOfDifference("i am a machine", "i am a robot") -> 7</code></p>
*
* <pre>
* StringUtils.indexOfDifference(null, null) = -1
* StringUtils.indexOfDifference("", "") = -1
* StringUtils.indexOfDifference("", "abc") = 0
* StringUtils.indexOfDifference("abc", "") = 0
* StringUtils.indexOfDifference("abc", "abc") = -1
* StringUtils.indexOfDifference("ab", "abxyz") = 2
* StringUtils.indexOfDifference("abcde", "abxyz") = 2
* StringUtils.indexOfDifference("abcde", "xyz") = 0
* </pre>
*
* @param str1 the first String, may be null
* @param str2 the second String, may be null
* @return the index where str2 and str1 begin to differ; -1 if they are equal
* @since 2.0
*/
public static int indexOfDifference(String str1, String str2) {
if (str1 == str2) {
return -1;
}
if (str1 == null || str2 == null) {
return 0;
}
int i;
for (i = 0; i < str1.length() && i < str2.length(); ++i) {
if (str1.charAt(i) != str2.charAt(i)) {
break;
}
}
if (i < str2.length() || i < str1.length()) {
return i;
}
return -1;
}
// Misc
//-----------------------------------------------------------------------
/**
* <p>Find the Levenshtein distance between two Strings.</p>
*
* <p>This is the number of changes needed to change one String into
* another, where each change is a single character modification (deletion,
* insertion or substitution).</p>
*
* <p>This implementation of the Levenshtein distance algorithm
* is from <a
href="http://www.merriampark.com/ld.htm">http://www.merriampark.com/ld.htm</a></p>
*
* <pre>
* StringUtils.getLevenshteinDistance(null, *) = IllegalArgumentException
* StringUtils.getLevenshteinDistance(*, null) = IllegalArgumentException
* StringUtils.getLevenshteinDistance("","") = 0
* StringUtils.getLevenshteinDistance("","a") = 1
* StringUtils.getLevenshteinDistance("aaapppp", "") = 7
* StringUtils.getLevenshteinDistance("frog", "fog") = 1
* StringUtils.getLevenshteinDistance("fly", "ant") = 3
* StringUtils.getLevenshteinDistance("elephant", "hippo") = 7
* StringUtils.getLevenshteinDistance("hippo", "elephant") = 7
* StringUtils.getLevenshteinDistance("hippo", "zzzzzzzz") = 8
* StringUtils.getLevenshteinDistance("hello", "hallo") = 1
* </pre>
*
* @param s the first String, must not be null
* @param t the second String, must not be null
* @return result distance
* @throws IllegalArgumentException if either String input <code>null</code>
*/
public static int getLevenshteinDistance(String s, String t) {
if (s == null || t == null) {
throw new IllegalArgumentException("Strings must not be null");
}
int d[][]; // matrix
int n; // length of s
int m; // length of t
int i; // iterates through s
int j; // iterates through t
char s_i; // ith character of s
char t_j; // jth character of t
int cost; // cost
// Step 1
n = s.length();
m = t.length();
if (n == 0) {
return m;
}
if (m == 0) {
return n;
}
d = new int[n + 1][m + 1];
// Step 2
for (i = 0; i <= n; i++) {
d[i][0] = i;
}
for (j = 0; j <= m; j++) {
d[0][j] = j;
}
// Step 3
for (i = 1; i <= n; i++) {
s_i = s.charAt(i - 1);
// Step 4
for (j = 1; j <= m; j++) {
t_j = t.charAt(j - 1);
// Step 5
if (s_i == t_j) {
cost = 0;
} else {
cost = 1;
}
// Step 6
d[i][j] = min(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1] + cost);
}
}
// Step 7
return d[n][m];
}
/**
* <p>Gets the minimum of three <code>int</code> values.</p>
*
* @param a value 1
* @param b value 2
* @param c value 3
* @return the smallest of the values
*/
private static int min(int a, int b, int c) {
// Method copied from NumberUtils to avoid dependency on subpackage
if (b < a) {
a = b;
}
if (c < a) {
a = c;
}
return a;
}
}
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