The 0 flag : Formatter Flags « Development « Java Tutorial

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2. Development
3. Formatter Flags

The 0 flag causes output to be padded with zeros rather than spaces.

The 0 flag can be used with all format specifiers except %n.

import java.util.Formatter;

public class MainClass {
  public static void main(String args[]) {
    Formatter fmt = new Formatter();

    fmt.format("%05d", 100);
    System.out.println(fmt);

  }
}

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