시소당

세자리 숫자마다 콤마찍는

public  class  Test
{
  
        public  static  void  main(String[]  args)
        {
                Test  test  =  new  Test();
              
                System.out.println(test.comma("1"));
                System.out.println(test.comma("12"));
                System.out.println(test.comma("123"));
                System.out.println(test.comma("1234"));
                System.out.println(test.comma("12345"));
                System.out.println(test.comma("123456"));
                System.out.println(test.comma("1234567"));
                System.out.println(test.comma("12345678"));
                System.out.println(test.comma("123456789"));
        }
  
        public  String  comma(String  str)
        {
                String  temp  =  reverseString(str);
                String  result  =  "";
  
                for(int  i  =  0  ;  i  <  temp.length()  ;  i  +=  3)  {
                        if(i  +  3  <  temp.length())  {
                                result  +=  temp.substring(i,  i  +  3)  +  ",";
                        }
                        else  {
                                result  +=  temp.substring(i);
                        }
                }
  
                return  reverseString(result);
        }
  
        private  String  reverseString(String  s)
        {
                return  new  StringBuffer(s).reverse().toString();
        }
  
}