java对日期Date类进行加减运算，年份加减，月份加减

import java.text.SimpleDateFormat;

import java.util.Calendar;

import java.util.Date;

public class DateTestUtil {

    

    public static void main(String[] args) throws Exception {

        

        SimpleDateFormat sdf=new SimpleDateFormat("yyyyMMdd");

        String str="20110823";

        Date dt=sdf.parse(str);

        Calendar rightNow = Calendar.getInstance();

        rightNow.setTime(dt);

        rightNow.add(Calendar.YEAR,-1);//日期减1年

        rightNow.add(Calendar.MONTH,3);//日期加3个月

        rightNow.add(Calendar.DAY_OF_YEAR,10);//日期加10天

        Date dt1=rightNow.getTime();

        String reStr = sdf.format(dt1);

        System.out.println(reStr);

    }