1.替换
private String a = "1234";
private String b = "1234567890";
String c = a.replaceAll(a,"9876");
System.out.prlintln(c);
打印结果:9876
2.去重
private String a = "1234";
private String b = "456";
List<String> list = new ArrayList;
list.add(a);
list.add(b);
HashSet<String> hs = new HashSet<String>(list); //此时已经去掉重复的数据保存在HashSet中
System.out.prlintln(hs);
打印结果:[123456]
3.去掉集合俩边的括号
String substring = hs.toString().substring(1,hs.toString().length() - 1);
Syetem.out.prlintln(substring);
打印结果:123456
4.结束APP:
System.exit(0);