StringBuffer

package com.company;

import java.util.Scanner;

    //13 insert (位置,插入的内容)

public class Demo03 {

/*

    * StringBuffer 是String的增强类，加了缓冲区，效率更高* @param args

* */

    public static void main(String[] args) {

StringBuffer sb =new StringBuffer("生活不止眼前的苟且");

        StringBuffer sb1 = sb.append(",");

        System.out.println(sb1);    //等价于System.out.println(sb1.toString());

        StringBuffer sb2 = sb1.append("还有诗和远方的田野");

        System.out.println(sb2);

        StringBuffer sb3 = sb2.append(false);

        System.out.println(sb3);

        System.out.println("请输入一串数字");

        Scanner sc =new Scanner(System.in);

        String s1 = sc.next();

        StringBuffer sb4 =new StringBuffer(s1);

        for (int i = sb4.length()-3 ; i >0 ; i ++ ) {

sb4.insert(i,",");

            System.out.println(sb4);

        }

}

}