将int读到0显示为0000

int读0000时显示为0，谢了下面一个转换的小程序：

public class num {public  String getNumber(int num){String result = "";switch ((num+"").length()) {case 1:result = "000" + num;break;case 2:result = "00" + num;break;case 3:result = "0" + num;break;case 4:result = "" + num;break;    // 此处代表编号已经超过了9999，从0重新开始default:result = "0000";break;}return result;}}

ArrayList<String> list = new ArrayList<String>();for (int i = 1; i <= 9999; i++) {    if (String.valueOf(i).length()==1) {        list.add("000"+i);    }else if (String.valueOf(i).length()==2){        list.add("00"+i);    }else if (String.valueOf(i).length()==3){        list.add("0"+i);    }else{        list.add(String.valueOf(i));    }     }