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How to add leading zeros to a number?

This example shows you how to use the String.format() method to add zero padding to a number. If you just want to print out the result you can use System.out.format(). This method is available since Java 1.5, so If you use a previous version you can use the NumberFormat class, see: How to format a number with leading zeros?.

package com.javacoderanch.example.lang;

public class LeadingZerosExample {
    public static void main(String[] args) {
	int number = 1500;
	// String format below will add leading zeros (the %0 syntax) to the number above. 
        // The length of the formatted string will be 7 characters.
	String formatted = String.format("%07d", number);
	System.out.println("Number with leading zeros: " + formatted);

For more information about the format syntax you can find it here.