Relative indexes are especially useful when creating custom time and date formats : Formatter Argument Index « Development « Java Tutorial

1. Java Tutorial
2. Development
3. Formatter Argument Index

Because of relative indexing, the argument cal need only be passed once, rather than three times.

import java.util.Calendar;
import java.util.Formatter;

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

    fmt.format("Today is day %te of %<tB, %<tY", cal);
    System.out.println(fmt);
  }
}

Today is day 1 of December, 2006