java calendar

from head first java 

import java.util.Calendar;public class XCalendar {public static void main(String[] args){Calendar c = Calendar.getInstance();c.set(2004, 0 , 7 , 15 ,40 );  //设置时间System.out.println("now date:" + c.getTime());long day1 = c.getTimeInMillis();day1 += 1000 * 60 * 60;c.setTimeInMillis(day1);  //以mills set timeSystem.out.println("now date:" + c.getTime());System.out.println("new Hour:" + c.get(Calendar.HOUR_OF_DAY));c.add(Calendar.DATE, 35);  //增加天数，会改变月份System.out.println("add 35 days:" + c.getTime());c.roll(Calendar.DATE, 35); //不改变月份情况下来增加天数。System.out.println("roll 35 days:" + c.getTime());c.set(Calendar.DATE, 1);  //手动设置日期System.out.println("after set 1：" + c.getTime());}}