15章实例9

import java.util.Scanner;public class J {public static void main(String[] args) {Scanner input=new Scanner(System.in);System.out.println("请输入一串数字:");String nums=input.next();StringBuffer str=new StringBuffer(nums);for(int i=str.length()-3;i>0;i=i-3){str.insert(i,',');}System.out.println(str);}}