JAVA加減日期

package test;

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

public class T {

	public static void main(String[] args) {
		Date date = new Date();
		System.out.println((new SimpleDateFormat("yyyy-MM-dd")).format(date));
		Calendar cal = Calendar.getInstance();
		cal.setTime(date);
		//加天
		cal.add(Calendar.DATE, 100);
		System.out.println((new SimpleDateFormat("yyyy-MM-dd")).format(cal.getTime()));
		//減天
		cal.add(Calendar.DATE, -100);
		System.out.println((new SimpleDateFormat("yyyy-MM-dd")).format(cal.getTime()));
	}

}