withformats.java

《A first book of java》by Gary J.Bronson 北大出版社

import java.text.*; // this is required to access the DecimalFormat class
public class WithFormats
{
  public static void main(String[] args)
  {
      // this next statement creates the default format
    DecimalFormat num = new DecimalFormat("000");
   
    System.out.println(num.format(6));
    System.out.println(num.format(18));
    System.out.println(num.format(124));
    System.out.println("---");
    System.out.println(num.format(6+18+124));
  }
}