Java Calendar

package com.qhong;

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

public class Main {
    public static void main(String[] args) throws Exception {
        DateFormat df=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss:SSS");
        System.out.println(df.format(new Date()));
        Calendar calendar=Calendar.getInstance();
        Date dt=calendar.getTime();
        System.out.println(df.format(dt));
        System.out.println(calendar.getWeekYear());
        System.out.println(calendar.getFirstDayOfWeek());
        System.out.println(calendar.getWeeksInWeekYear());
        System.out.println("====================");
        System.out.println(calendar.get(Calendar.YEAR));
        System.out.println(calendar.get(Calendar.MONTH));
        System.out.println(calendar.get(Calendar.DAY_OF_MONTH));
        System.out.println(calendar.get(Calendar.DAY_OF_WEEK));
        System.out.println(calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH));
        System.out.println(calendar.get(Calendar.DAY_OF_YEAR));
        System.out.println("====================");
        System.out.println(calendar.get(Calendar.DATE));
        System.out.println(calendar.get(Calendar.HOUR));
        System.out.println(calendar.get(Calendar.HOUR_OF_DAY));
        System.out.println(calendar.get(Calendar.MINUTE));
        System.out.println(calendar.get(Calendar.SECOND));
        System.out.println("====================");
        System.out.println(calendar.get(Calendar.MILLISECOND));
        Calendar NewCalendar=Calendar.getInstance();
        NewCalendar.setTime(new Date());
        System.out.println(df.format(NewCalendar.getTime()));
        NewCalendar.add(Calendar.YEAR,-1);
        System.out.println(df.format(NewCalendar.getTime()));
        NewCalendar.add(Calendar.MONTH,2);
        System.out.println(df.format(NewCalendar.getTime()));
        NewCalendar.add(Calendar.DATE,3);
        //后者大，显示 -1  
        System.out.println(df.format(NewCalendar.getTime()));
        System.out.println("时间比较："+NewCalendar.compareTo(calendar));
        //前者大，显示 1
        NewCalendar.add(Calendar.YEAR,1);
        System.out.println("时间比较："+NewCalendar.compareTo(calendar));
    }
}

2017-03-13 22:36:08:393
2017-03-13 22:36:08:394
2017
1
52
====================
2017
2
13
2
2
72
====================
13
10
22
36
8
====================
394
2017-03-13 22:36:08:394
2016-03-13 22:36:08:394
2016-05-13 22:36:08:394
2016-05-16 22:36:08:394
时间比较：-1
时间比较：1