Illustration of basic date arithmetics in Java.

DateAritmethics

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;


public class DateAritmethics {

	public static void main(String[] args) {
	
		// Subtract three months from today.
		//
		String dateFormat = "yyyy.MM.dd 'at' HH:mm:ss zzzz";
		Date today = new Date();
		Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("CET"));
		cal.setTime(today);
		cal.add(Calendar.MONTH, -3);
		Date before = cal.getTime();
		System.out.println("Today is : "+ new SimpleDateFormat(dateFormat).format(today));
		System.out.println("-3 months: "+ new SimpleDateFormat(dateFormat).format(before));

	}

}