Add leading zeros to a number : Number Format « Data Type « Java Tutorial

public class Main {
  public static void main(String[] args) {
    int number = 1500;

    String formatted = String.format("%07d", number);

    System.out.println("Number with leading zeros: " + formatted);

2.14.Number Format
2.14.1.Number formatting helps make your numbers more readable.
2.14.2.Specifying Precision
2.14.3.Applied to strings, the precision specifier specifies the maximum field length
2.14.4.Illustrating the precision specifier
2.14.5.Add leading zeros to a number
2.14.8.NumberFormat: Minimum Integer Digits, Maximum/Minimum Fraction Digits
2.14.9.Number format with FieldPosition
2.14.11.A number formatter for logarithmic values. This formatter does not support parsing.
2.14.12.Format a percentage for presentation to the user
2.14.13.Get Percent Value
2.14.14.Helper class for format number and currency