Java int type format add leading zero

//package com.demo2s;

import java.text.DecimalFormat;

public class Main {
    public static void main(String[] argv) throws Exception {
        int num = 2;
        System.out.println(addLeadingZero(num));
    }//from ww w  . jav a  2s .  c  o  m

    public static String addLeadingZero(int num) {
        DecimalFormat df = new DecimalFormat("00000");
        return df.format(num);
    }
}

//package com.demo2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        String aString = "";
        int aAmountOfZeros = 2;
        System.out.println(addLeadingZero(aString, aAmountOfZeros));
    }/*from   w w w . j  a v  a 2s.  co  m*/

    public static String addLeadingZero(String aString, int aAmountOfZeros) {
        final int stringLength = aString.length();

        if (stringLength < aAmountOfZeros) {
            for (int i = 0, l = aAmountOfZeros - stringLength; i < l; ++i) {
                aString = "0" + aString;
            }
        }
        return aString;
    }
}

//package com.demo2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        int integer = 2;
        System.out.println(addLeadingZeroIfNecessary(integer));
    }//from w  w  w  . ja  v a 2s . co  m

    public static String addLeadingZeroIfNecessary(int integer) {
        if (integer < 10) {
            return "0" + integer;
        } else {
            return "" + integer;
        }
    }
}