字符串修改成1111,111,111形式（3、4、5等类似）

    public String repalceStr(String str){
        String arepalce = "";
        if(str.length()<=3){
            arepalce = str;
        }else{
            String astr1 = "";
            String astr2 = "";
            int remainder = str.length()%3;
            if(remainder==0){
               arepalce = new ExfinanceServiceImpl().allThreeStr(str);
            }else{
               astr1 = str.substring(0, remainder);
               astr2 = str.substring(remainder, str.length());
               arepalce = new ExfinanceServiceImpl().allThreeStr(astr2);
               arepalce=astr1+","+arepalce;
            }
        }
        return arepalce;
    }
    
    public String allThreeStr(String threeStr){
        String arepalce = "";
        int c = threeStr.length()/3;
        for(int i=0;i<=c-1;i++){
            String subi = threeStr.substring(i*3, (i+1)*3);
            if(i!=c-1){
                arepalce +=subi+",";
            }else{
                arepalce +=subi;
            }
        }
        return arepalce;
    }