Substract week from current date in Java

/*from  w ww .ja  v a2  s  .c  o  m*/
import java.util.Calendar;

public class Main {

  public static void main(String[] args) {
    Calendar now = Calendar.getInstance();

    System.out.println("Current date : " + (now.get(Calendar.MONTH) + 1) + "-"
        + now.get(Calendar.DATE) + "-" + now.get(Calendar.YEAR));

    System.out.println("Current week of month is : " + now.get(Calendar.WEEK_OF_MONTH));
    System.out.println("Current week of year is : " + now.get(Calendar.WEEK_OF_YEAR));

    now = Calendar.getInstance();
    now.add(Calendar.WEEK_OF_YEAR, -50);
    System.out.println("date before 50 weeks : " + (now.get(Calendar.MONTH) + 1) + "-"
        + now.get(Calendar.DATE) + "-" + now.get(Calendar.YEAR));
  }
}