String类

Eclipse 的常用快捷键

Ctrl+F 查找（替换）
Alt + / 自动补全
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Ctrl+O：快速跳转
ctrl+.及ctrl+1：下一个错误及快速修改

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import java.util.Date;public class StringTest {    public static void main(String[] args) {        String a = new String("aaaa");        System.out.println(a);        char[] charArray = {'s', 'r', 't', 'd'};        String b = new String(charArray);        System.out.println(b);        String c = new String(charArray, 1,2);        System.out.println(c);        byte[] byteArray = {-26,-126,-88,-27,-91,-67};        String d = new String(byteArray);        System.out.println(d);        String s = "您好";        byte[] by = s.getBytes();        for(int i = 0; i < by.length; i++){            System.out.print (by[i]+ s);        }        System.out.println();        String str = "abc DEF";        System.out.println(str.toLowerCase());//转小写        System.out.println(str.toUpperCase());//转大写        //格式化        String str1 = String.format("字母a大写：%c", 'X');        String str2 = String.format("123+456=%d", 123 + 456);        String str3 = String.format("PI取二位小数：%.2f", Math.PI);        String str4 = String.format("2<3吗？%b", 2 < 3);        System.out.println(str1);        System.out.println(str2);        System.out.println(str3);        System.out.println(str4);        //CharAt 获取指定字符        String aa = "Students";        System.out.println(aa.charAt(2));        //查找位置        System.out.println(aa.indexOf("t"));        System.out.println(aa.indexOf("t", 3));        System.out.println(aa.lastIndexOf("t"));        //截取字符串        System.out.println(aa.substring(1, 3));        //获取字符串长度        System.out.println("aa长度：" + aa.length());        //连接字符串        String bb = " and Teacher";        System.out.println(aa.concat(bb));        System.out.println(aa + bb);        //判断字符串结尾/开始        String fileName="ks.jpg";        System.out.println(fileName.endsWith(".jpg"));        System.out.println(fileName.startsWith("k"));        //比较字符串        String s1 = "ABC",s2 = "abc";        System.out.println(s1.equals(s2));        System.out.println(s1.equalsIgnoreCase(s2));        //去空格        System.out.println(bb.trim());//去首尾客格        //替换         System.out.println(aa.replace("s", ""));        //日期格式化        Date data = new Date();        String fs = String.format("%tF", data);        System.out.println(data);        System.out.println(fs);        //年月日 时分秒        System.out.print( String.format("%tY", data));        System.out.print( String.format("%tB", data));        System.out.println( String.format("%td", data));        System.out.println( String.format("%tH", data));        System.out.println( String.format("%tM", data));        System.out.println( String.format("%tS", data));        //字符串 分割 split    }}输出:aaaasrtdrt您好-26您好-126您好-88您好-27您好-91您好-67您好abc defABC DEF字母a大写：X123+456=579PI取二位小数：3.142<3吗？trueu166tuaa长度：8Students and TeacherStudents and Teachertruetruefalsetrueand TeacherStudentMon Jul 24 23:25:45 CST 20172017-07-242017七月24232545