Calendar类常用API

妖狐艹你老母 2022-04-06 04:14 407阅读 0赞

import java.util.Calendar;
    import java.util.Date;
    
    public class CalendarTest {
    
    	public static void main(String[] args) {
    		test();
    		System.out.println("--------------");
    		test1();
    		System.out.println("--------------");
    		test2();
    		System.out.println("--------------");
    		test3();
    		System.out.println("--------------");
    		test4();
    		System.out.println("--------------");
    		System.out.println(test5(new Date(), -1));
    	}
    
    	// 3s后
    	public static void test() {
    		long start = System.currentTimeMillis() + 3000;
    		Date date = new Date(start);
    		System.out.println(new Date());
    		System.out.println(date);
    	}
    
    	// 基本用法，获取年月日时分秒星期
    	public static void test1() {
    		Calendar calendar = Calendar.getInstance();
    		// 获取年
    		int year = calendar.get(Calendar.YEAR);
    
    		// 获取月，这里需要需要月份的范围为0~11，因此获取月份的时候需要+1才是当前月份值
    		int month = calendar.get(Calendar.MONTH) + 1;
    
    		// 获取日
    		int day = calendar.get(Calendar.DAY_OF_MONTH);
    
    		// 获取时
    		int hour2 = calendar.get(Calendar.HOUR_OF_DAY); // 24小时表示
    		int hour = calendar.get(Calendar.HOUR);
    
    		// 获取分
    		int minute = calendar.get(Calendar.MINUTE);
    
    		// 获取秒
    		int second = calendar.get(Calendar.SECOND);
    
    		// 获取毫秒
    		int milliSecond = calendar.get(Calendar.MILLISECOND);
    
    		// 星期，英语国家星期从星期日开始计算
    		int weekday = calendar.get(Calendar.DAY_OF_WEEK);
    
    		System.out.println("现在是" + year + "年" + month + "月" + day + "日" + hour2 + "(" + hour + ")" + "时" + minute + "分"
    				+ second + "秒" + milliSecond + "毫秒" + "星期" + weekday);
    	}
    
    	// 一年后的今天
    	public static void test2() {
    		Calendar calendar = Calendar.getInstance();
    		calendar.add(Calendar.YEAR, 1);
    
    		Date time = calendar.getTime();
    		System.out.println("一年后的今天:" + time);
    	}
    
    	// 这个月的第一天
    	public static void test3() {
    		Calendar calendar = Calendar.getInstance();
    		calendar.set(Calendar.DAY_OF_MONTH, 1);
    		calendar.set(Calendar.HOUR_OF_DAY, 0);
    		calendar.set(Calendar.MINUTE, 0);
    		calendar.set(Calendar.SECOND, 0);
    		// calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), 1);
    		System.out.println("这个月的第一天:" + calendar.getTime());
    	}
    
    	// 这个月的最后一天
    	public static void test4() {
    		Calendar calendar = Calendar.getInstance();
    		calendar.add(Calendar.MONTH, 1);
    		calendar.set(Calendar.DAY_OF_MONTH, 1);
    		calendar.set(Calendar.HOUR_OF_DAY, 0);
    		calendar.set(Calendar.MINUTE, 0);
    		calendar.set(Calendar.SECOND, 0);
    		calendar.set(Calendar.SECOND, -1);
    		System.out.println("这个月的最后一天:" + calendar.getTime());
    	}
    	
    	 // 在特定日期的基础上增加或者减少天数
    	public static Date test5(Date date, Integer days) {
    		Calendar calendar = Calendar.getInstance();
    		calendar.setTime(date);
    		if (days != null) {
    			calendar.add(Calendar.DAY_OF_MONTH, days);
    		}
    		return calendar.getTime();
    	}
    
    }

> Fri Dec 07 21:38:04 CST 2018  
> Fri Dec 07 21:38:07 CST 2018  
> \--------------  
> 现在是2018年12月7日21(9)时38分4秒405毫秒星期6  
> \--------------  
> 一年后的今天:Sat Dec 07 21:38:04 CST 2019  
> \--------------  
> 这个月的第一天:Sat Dec 01 00:00:00 CST 2018  
> \--------------  
> 这个月的最后一天:Mon Dec 31 23:59:59 CST 2018  
> \--------------  
> Thu Dec 06 21:38:04 CST 2018