java学习：日期的运算代码

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

public class HelloWorld {

    public static void main(String[] args) {

        //指定时间输出格式
        SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");

        Date dt = new Date();
        System.out.println("当前时间：" + sdf.format(dt));

        Calendar rightNow = Calendar.getInstance();
        rightNow.setTime(dt);        

        rightNow.add(Calendar.YEAR,-1);//当时日期减1年
        System.out.println("减1年：" + sdf.format(rightNow.getTime()));

        rightNow.add(Calendar.MONTH,3);//(在刚才的结果上)再加3个月
        System.out.println("再加3个月：" + sdf.format(rightNow.getTime()));

        rightNow.add(Calendar.DAY_OF_YEAR,10);//(在刚才的结果上)再加10天        
        System.out.println("再加10天：" + sdf.format(rightNow.getTime()));

 
    }
}