Question

java中的Calendar如何使用的？

我想获取现在的时间和现在到一年前的时间。比如现在是2011-02-12 08:55然后到2010-02-12 08:55

Answer 1

package pack.java.calendar.demo;

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

public class CalendarDemo {
private static SimpleDateFormat date_format = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
public static void main(String[] args) {

//获取calendar实例;
Calendar calendar = Calendar.getInstance();

//判断calendar是不是GregorianCalendar类的实例;
if(calendar instanceof GregorianCalendar){
System.out.println("属于GregorianCalendar类的实例!");
}

//从calendar对象中获得date对象，当前时间;
Date dates = calendar.getTime();

//格式化时间;
String date_str= date_format.format(dates);
System.out.println(date_str);

//设置月份05；代表日历的月份6月，因为月份从0开始。
calendar.set(Calendar.MONTH, 05);

int months = calendar.get(Calendar.MONTH);
System.out.println(months); //输出05;

//设置日期为2011-07-24 09：59:50
calendar.set(2011, 06, 24, 9, 59, 50);
String getDate = date_format.format(calendar.getTime());
System.out.println(getDate); //输出2011-07-24 09:59:50;

//比较日前大小;
if(new Date().getTime() > calendar.getTimeInMillis()){
System.out.println("当前日期在后!");
}else{
System.out.println("当前日期在前!");
}

//设置当前时间为:2011-07-24 11:06:00
calendar.setTime(new Date());
int year = calendar.get(Calendar.YEAR); //获取年;
int month = calendar.get(Calendar.MONTH); //获取月;
int date = calendar.get(Calendar.DATE); //获取天;
int hour = calendar.get(Calendar.HOUR); //获取小时;
int minute = calendar.get(Calendar.MINUTE); //获取分钟;
int second = calendar.get(Calendar.SECOND); //获取秒钟;
int hour_of_day = calendar.get(Calendar.HOUR_OF_DAY); //第几个小时，
int day_of_month = calendar.get(Calendar.DAY_OF_MONTH); //这天，在一个月内是第几天.
int day_of_week = calendar.get(Calendar.DAY_OF_WEEK); //这天，在一周内，是第几天.
int day_of_year = calendar.get(Calendar.DAY_OF_YEAR); //这天，在一年内，是第几天。
int week_of_year = calendar.get(Calendar.WEEK_OF_YEAR); //这周，在一年内是第几周;
int week_of_month = calendar.get(Calendar.WEEK_OF_MONTH);//这周，在这个月是第几周;以以星为标准；
int zone_offset = calendar.get(Calendar.ZONE_OFFSET); //获取时区;
int day_of_week_in_month = calendar.get(Calendar.DAY_OF_WEEK_IN_MONTH); //某月中第几周，按这个月1号算，1号起就是第1周，8号起就是第2周。以月份天数为标准
int r = calendar.get(Calendar.AM_PM);
if(r==calendar.AM){
System.out.println("现在是上午");
}

if(r==calendar.PM){
System.out.println("现在是下午");
}
System.out.println("==================================================");
System.out.println(year);
System.out.println(month);
System.out.println(date);
System.out.println(hour);
System.out.println(minute);
System.out.println(second);
System.out.println(hour_of_day);
System.out.println(day_of_month);
System.out.println(day_of_week);
System.out.println(day_of_year);
System.out.println(week_of_year);
System.out.println(week_of_month);
System.out.println(zone_offset);
System.out.println(day_of_week_in_month);
}
}

Answer 2

Calendar.getInstance().getTime(),取当前时间Calendar d=Calendar.getInstance();
System.out.println(d.getTime());
d.add(Calendar.YEAR, -1);年份减1
System.out.print(d.getTime());