String类型常用方法汇总

String demoString = "ceshibaixiaosheng";

//判断字符串是否包含 false
System.out.println(demoString.contains("t"));

//字符串相加  也可以使用+
String dsg = demoString.concat(" very good");
System.out.println(dsg); //ceshibaixiaosheng very good

//字符串长度 17
int length = demoString.length();
System.out.println(length);

//比较字符串是否相等  false
System.out.println("baixiaosheng".equals(demoString));

//截取字符串      角标从0开始
String str1 = demoString.substring(5,8);
System.out.println(str1); //bai
//从5开始到结尾
String str2 = demoString.substring(5);
System.out.println(str2);

//判断是否以某字符串开头
boolean sw = demoString.startsWith("ceshi");
System.out.println(sw);

//判断是否以某字符串结尾
boolean ew = demoString.endsWith("baixiaosheng");
System.out.println(ew);

//找出字符串在字符串中第一次出现的位置    	如果没有返回-1
int indexOf = demoString.indexOf("bai");
System.out.println(indexOf); //5

//找出字符串中最后一次出现的位置
int lastIndex = demoString.lastIndexOf("e");
System.out.println(lastIndex); //14

//字符串字母都变成大写    CESHIBAIXIAOSHENG
System.out.println(demoString.toUpperCase());

//字符串字母都变成小写   ceshibaixiaosheng
System.out.println(demoString.toLowerCase());

//去掉首尾的空格
System.out.println(" baixiaosheng ".trim());

//替换字符串
String replace = demoString.replace("ceshi","AA");
System.out.println(replace); //AAbaixiaosheng

//将字符串中的第一个出现的字符串替换掉
String replaceF = demoString.replaceFirst("e","3");
System.out.println(replaceF); //c3shibaixiaosheng

//替换中所有的
String replaceAll = demoString.replaceAll("e","6");
System.out.println(replaceAll); //c6shibaixiaosh6ng