/* * Copyright 2002-2007 the original author or authors. * * 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.springframework.util;import java.util.Collection;import java.util.Map;/** * Assertion utility class that assists in validating arguments. * Useful for identifying programmer errors early and clearly at runtime. * * <p>For example, if the contract of a public method states it does not * allow <code>null</code> arguments, Assert can be used to validate that * contract. Doing this clearly indicates a contract violation when it * occurs and protects the class's invariants. * * <p>Typically used to validate method arguments rather than configuration * properties, to check for cases that are usually programmer errors rather than * configuration errors. In contrast to config initialization code, there is * usally no point in falling back to defaults in such methods. * * <p>This class is similar to JUnit's assertion library. If an argument value is * deemed invalid, an {@link IllegalArgumentException} is thrown (typically). * For example: * * <pre class="code"> * Assert.notNull(clazz, "The class must not be null"); * Assert.isTrue(i > 0, "The value must be greater than zero");</pre> * * Mainly for internal use within the framework; consider Jakarta's Commons Lang * >= 2.0 for a more comprehensive suite of assertion utilities. * * @author Keith Donald * @author Juergen Hoeller * @author Colin Sampaleanu * @author Rob Harrop * @since 1.1.2 */public abstract class Assert {/** * Assert a boolean expression, throwing <code>IllegalArgumentException</code> * if the test result is <code>false</code>. * <pre class="code">Assert.isTrue(i > 0, "The value must be greater than zero");</pre> * @param expression a boolean expression * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if expression is <code>false</code> */public static void isTrue(boolean expression, String message) {if (!expression) {throw new IllegalArgumentException(message);}}/** * Assert a boolean expression, throwing <code>IllegalArgumentException</code> * if the test result is <code>false</code>. * <pre class="code">Assert.isTrue(i > 0);</pre> * @param expression a boolean expression * @throws IllegalArgumentException if expression is <code>false</code> */public static void isTrue(boolean expression) {isTrue(expression, "[Assertion failed] - this expression must be true");}/** * Assert that an object is <code>null</code> . * <pre class="code">Assert.isNull(value, "The value must be null");</pre> * @param object the object to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the object is not <code>null</code> */public static void isNull(Object object, String message) {if (object != null) {throw new IllegalArgumentException(message);}}/** * Assert that an object is <code>null</code> . * <pre class="code">Assert.isNull(value);</pre> * @param object the object to check * @throws IllegalArgumentException if the object is not <code>null</code> */public static void isNull(Object object) {isNull(object, "[Assertion failed] - the object argument must be null");}/** * Assert that an object is not <code>null</code> . * <pre class="code">Assert.notNull(clazz, "The class must not be null");</pre> * @param object the object to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the object is <code>null</code> */public static void notNull(Object object, String message) {if (object == null) {throw new IllegalArgumentException(message);}}/** * Assert that an object is not <code>null</code> . * <pre class="code">Assert.notNull(clazz);</pre> * @param object the object to check * @throws IllegalArgumentException if the object is <code>null</code> */public static void notNull(Object object) {notNull(object, "[Assertion failed] - this argument is required; it must not be null");}/** * Assert that the given String is not empty; that is, * it must not be <code>null</code> and not the empty String. * <pre class="code">Assert.hasLength(name, "Name must not be empty");</pre> * @param text the String to check * @param message the exception message to use if the assertion fails * @see StringUtils#hasLength */public static void hasLength(String text, String message) {if (!StringUtils.hasLength(text)) {throw new IllegalArgumentException(message);}}/** * Assert that the given String is not empty; that is, * it must not be <code>null</code> and not the empty String. * <pre class="code">Assert.hasLength(name);</pre> * @param text the String to check * @see StringUtils#hasLength */public static void hasLength(String text) {hasLength(text,"[Assertion failed] - this String argument must have length; it must not be null or empty");}/** * Assert that the given String has valid text content; that is, it must not * be <code>null</code> and must contain at least one non-whitespace character. * <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre> * @param text the String to check * @param message the exception message to use if the assertion fails * @see StringUtils#hasText */public static void hasText(String text, String message) {if (!StringUtils.hasText(text)) {throw new IllegalArgumentException(message);}}/** * Assert that the given String has valid text content; that is, it must not * be <code>null</code> and must contain at least one non-whitespace character. * <pre class="code">Assert.hasText(name, "'name' must not be empty");</pre> * @param text the String to check * @see StringUtils#hasText */public static void hasText(String text) {hasText(text,"[Assertion failed] - this String argument must have text; it must not be null, empty, or blank");}/** * Assert that the given text does not contain the given substring. * <pre class="code">Assert.doesNotContain(name, "rod", "Name must not contain 'rod'");</pre> * @param textToSearch the text to search * @param substring the substring to find within the text * @param message the exception message to use if the assertion fails */public static void doesNotContain(String textToSearch, String substring, String message) {if (StringUtils.hasLength(textToSearch) && StringUtils.hasLength(substring) &&textToSearch.indexOf(substring) != -1) {throw new IllegalArgumentException(message);}}/** * Assert that the given text does not contain the given substring. * <pre class="code">Assert.doesNotContain(name, "rod");</pre> * @param textToSearch the text to search * @param substring the substring to find within the text */public static void doesNotContain(String textToSearch, String substring) {doesNotContain(textToSearch, substring,"[Assertion failed] - this String argument must not contain the substring [" + substring + "]");}/** * Assert that an array has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre class="code">Assert.notEmpty(array, "The array must have elements");</pre> * @param array the array to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements */public static void notEmpty(Object[] array, String message) {if (ObjectUtils.isEmpty(array)) {throw new IllegalArgumentException(message);}}/** * Assert that an array has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre class="code">Assert.notEmpty(array);</pre> * @param array the array to check * @throws IllegalArgumentException if the object array is <code>null</code> or has no elements */public static void notEmpty(Object[] array) {notEmpty(array, "[Assertion failed] - this array must not be empty: it must contain at least 1 element");}/** * Assert that an array has no null elements. * Note: Does not complain if the array is empty! * <pre class="code">Assert.noNullElements(array, "The array must have non-null elements");</pre> * @param array the array to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the object array contains a <code>null</code> element */public static void noNullElements(Object[] array, String message) {if (array != null) {for (int i = 0; i < array.length; i++) {if (array[i] == null) {throw new IllegalArgumentException(message);}}}}/** * Assert that an array has no null elements. * Note: Does not complain if the array is empty! * <pre class="code">Assert.noNullElements(array);</pre> * @param array the array to check * @throws IllegalArgumentException if the object array contains a <code>null</code> element */public static void noNullElements(Object[] array) {noNullElements(array, "[Assertion failed] - this array must not contain any null elements");}/** * Assert that a collection has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre> * @param collection the collection to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements */public static void notEmpty(Collection collection, String message) {if (CollectionUtils.isEmpty(collection)) {throw new IllegalArgumentException(message);}}/** * Assert that a collection has elements; that is, it must not be * <code>null</code> and must have at least one element. * <pre class="code">Assert.notEmpty(collection, "Collection must have elements");</pre> * @param collection the collection to check * @throws IllegalArgumentException if the collection is <code>null</code> or has no elements */public static void notEmpty(Collection collection) {notEmpty(collection,"[Assertion failed] - this collection must not be empty: it must contain at least 1 element");}/** * Assert that a Map has entries; that is, it must not be <code>null</code> * and must have at least one entry. * <pre class="code">Assert.notEmpty(map, "Map must have entries");</pre> * @param map the map to check * @param message the exception message to use if the assertion fails * @throws IllegalArgumentException if the map is <code>null</code> or has no entries */public static void notEmpty(Map map, String message) {if (CollectionUtils.isEmpty(map)) {throw new IllegalArgumentException(message);}}/** * Assert that a Map has entries; that is, it must not be <code>null</code> * and must have at least one entry. * <pre class="code">Assert.notEmpty(map);</pre> * @param map the map to check * @throws IllegalArgumentException if the map is <code>null</code> or has no entries */public static void notEmpty(Map map) {notEmpty(map, "[Assertion failed] - this map must not be empty; it must contain at least one entry");}/** * Assert that the provided object is an instance of the provided class. * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre> * @param clazz the required class * @param obj the object to check * @throws IllegalArgumentException if the object is not an instance of clazz * @see Class#isInstance */public static void isInstanceOf(Class clazz, Object obj) {isInstanceOf(clazz, obj, "");}/** * Assert that the provided object is an instance of the provided class. * <pre class="code">Assert.instanceOf(Foo.class, foo);</pre> * @param type the type to check against * @param obj the object to check * @param message a message which will be prepended to the message produced by * the function itself, and which may be used to provide context. It should * normally end in a ": " or ". " so that the function generate message looks * ok when prepended to it. * @throws IllegalArgumentException if the object is not an instance of clazz * @see Class#isInstance */public static void isInstanceOf(Class type, Object obj, String message) {notNull(type, "Type to check against must not be null");if (!type.isInstance(obj)) {throw new IllegalArgumentException(message +"Object of class [" + (obj != null ? obj.getClass().getName() : "null") +"] must be an instance of " + type);}}/** * Assert that <code>superType.isAssignableFrom(subType)</code> is <code>true</code>. * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre> * @param superType the super type to check * @param subType the sub type to check * @throws IllegalArgumentException if the classes are not assignable */public static void isAssignable(Class superType, Class subType) {isAssignable(superType, subType, "");}/** * Assert that <code>superType.isAssignableFrom(subType)</code> is <code>true</code>. * <pre class="code">Assert.isAssignable(Number.class, myClass);</pre> * @param superType the super type to check against * @param subType the sub type to check * @param message a message which will be prepended to the message produced by * the function itself, and which may be used to provide context. It should * normally end in a ": " or ". " so that the function generate message looks * ok when prepended to it. * @throws IllegalArgumentException if the classes are not assignable */public static void isAssignable(Class superType, Class subType, String message) {notNull(superType, "Type to check against must not be null");if (subType == null || !superType.isAssignableFrom(subType)) {throw new IllegalArgumentException(message + subType + " is not assignable to " + superType);}}/** * Assert a boolean expression, throwing <code>IllegalStateException</code> * if the test result is <code>false</code>. Call isTrue if you wish to * throw IllegalArgumentException on an assertion failure. * <pre class="code">Assert.state(id == null, "The id property must not already be initialized");</pre> * @param expression a boolean expression * @param message the exception message to use if the assertion fails * @throws IllegalStateException if expression is <code>false</code> */public static void state(boolean expression, String message) {if (!expression) {throw new IllegalStateException(message);}}/** * Assert a boolean expression, throwing {@link IllegalStateException} * if the test result is <code>false</code>. * <p>Call {@link #isTrue(boolean)} if you wish to * throw {@link IllegalArgumentException} on an assertion failure. * <pre class="code">Assert.state(id == null);</pre> * @param expression a boolean expression * @throws IllegalStateException if the supplied expression is <code>false</code> */public static void state(boolean expression) {state(expression, "[Assertion failed] - this state invariant must be true");}}
