Answer by Dinesh Lomte for How can I pad an integer with zeros on the left?

Here is another way to pad an integer with zeros on the left. You can increase the number of zeros as per your convenience. Have added a check to return the same value as is in case of negative number or a value greater than or equals to zeros configured. You can further modify as per your requirement.

/** *  * @author Dinesh.Lomte * */public class AddLeadingZerosToNum {    /**     *      * @param args     */    public static void main(String[] args) {        System.out.println(getLeadingZerosToNum(0));        System.out.println(getLeadingZerosToNum(7));        System.out.println(getLeadingZerosToNum(13));        System.out.println(getLeadingZerosToNum(713));        System.out.println(getLeadingZerosToNum(7013));        System.out.println(getLeadingZerosToNum(9999));    }    /**     *      * @param num     * @return     */    private static String getLeadingZerosToNum(int num) {        // Initializing the string of zeros with required size        String zeros = new String("0000");        // Validating if num value is less then zero or if the length of number         // is greater then zeros configured to return the num value as is        if (num < 0 || String.valueOf(num).length() >= zeros.length()) {            return String.valueOf(num);        }        // Returning zeros in case if value is zero.        if (num == 0) {            return zeros;        }        return new StringBuilder(zeros.substring(0, zeros.length() -                 String.valueOf(num).length())).append(                        String.valueOf(num)).toString();    }}

Input

0

7

13

713

7013

9999

Output

0000

0007

0013

7013

9999