[Java] 常用类-01 String / StringBuffer

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package com.bjsxt.chap6;/** * @author hp * */public class Test {    public static void main(String[] args) {        String s1 = "hello";        String s2 = "world!";        String s3 = "hello";        System.out.println(s1 == s3);                s1 = new String("hello");        s2 = new String("hello");        System.out.println(s1 == s3);        System.out.println(s1.equals(s3));                char c[] = {'s', 'u', 'n', ' ', 'j', 'a', 'v', 'a'};        String s4 = new String(c);        String s5 = new String(c, 4, 3); // 数组， 下标， 长度        System.out.println(s4 + '\n' + s5);                System.out.println(s4.charAt(1));        System.out.println(s4.length());        System.out.println(s4.indexOf("java"));                System.out.println(s4.replaceAll("sun", "oracle"));    }}

package com.bjsxt.chap6;public class TestStringCase {    public static void main(String[] args) {        String s = "ABAabb$&^$#BAAb898B#@%aa";        int cU = 0, cL = 0, cO = 0;        for (int i = 0; i < s.length(); i++) {            char c = s.charAt(i);            if (c >= 'A' && c <= 'Z') {                cU++;            } else if (c >= 'a' && c <= 'z') {                cL++;            } else {                cO++;            }        }        System.out.println("小写：" + cL);        System.out.println("大写：" + cU);        System.out.println("其他：" + cO);                int lCount = 0, uCount = 0, oCount = 0;        for (int i = 0; i < s.length(); i++) {            char c = s.charAt(i);            if (Character.isLowerCase(c)) {                lCount++;            } else if (Character.isUpperCase(c)) {                uCount++;            } else {                oCount++;            }        }                System.out.println("小写：" + lCount);        System.out.println("大写：" + uCount);        System.out.println("其他：" + oCount);                String ss = "sunjavahpjavaokjavajjavahahajavajavagoodjava";                String sToFind = "java";        int count = 0;        int index = -1;                while((index = ss.indexOf(sToFind)) != -1) {            ss = ss.substring(index + sToFind.length());            count ++;        }                System.out.println(count);    }}

package com.bjsxt.chap6;public class TestBuffer {    public static void main(String[] args) {        String s = "Mircosoft";        char arr[] = {'a', 'b', 'c'};        StringBuffer sb1 = new StringBuffer(s);        sb1.append('/').append("IBM");        System.out.println(sb1);        StringBuffer sb2 = new StringBuffer("数字");        for (int i = 0; i <= 9; i++) {            sb2.append(i);        }        System.out.println(sb2);                sb2.delete(8, 11).insert(0, arr);                System.out.println(sb2);        System.out.println(sb2.reverse());    }}

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