Common objects (an overview and usage of the Calendar class)

Calendar: It provides methods for converting between a specific instant and a set of calendar fields such as YEAR, MONTH, DAY_OF_MONTH, HOUR, etc., and for manipulating calendar fields (for example, to get the date of the next week).
 * public int get(int field): Returns the value of the given calendar field. Each calendar field in the calendar class is a static member variable and is of type int.        

public class CalendarDemo {
	public static void main(String[] args) {
		// 其日历字段已由当前日期和时间初始化：
		Calendar rightNow = Calendar.getInstance(); // 子类对象
 
		// 获取年
		int year = rightNow.get(Calendar.YEAR);
		// 获取月
		int month = rightNow.get(Calendar.MONTH);
		// 获取日
		int date = rightNow.get(Calendar.DATE);
 
		System.out.println(year + "年" + (month + 1) + "月" + date + "日");
	}
}
 
/*
 * abstract class Person { public static Person getPerson() { return new
 * Student(); } }
 * 
 * class Student extends Person {
 * 

/*
 * public void add(int field,int amount): Operate the current calendar according to the given calendar field and corresponding time.
 * public final void set(int year, int month, int date): set the year, month and day of the current calendar
 */ 
 

package cn.itcast_02;
 
import java.util.Calendar;
 
/*
 * public void add(int field,int amount):根据给定的日历字段和对应的时间，来对当前的日历进行操作。
 * public final void set(int year,int month,int date):设置当前日历的年月日
 */
public class CalendarDemo {
	public static void main(String[] args) {
		// 获取当前的日历时间
		Calendar c = Calendar.getInstance();
 
		// 获取年
		int year = c.get(Calendar.YEAR);
		// 获取月
		int month = c.get(Calendar.MONTH);
		// 获取日
		int date = c.get(Calendar.DATE);
		System.out.println(year + "年" + (month + 1) + "月" + date + "日");
 
		// // 三年前的今天
		// c.add(Calendar.YEAR, -3);
		// // 获取年
		// year = c.get(Calendar.YEAR);
		// // 获取月
		// month = c.get(Calendar.MONTH);
		// // 获取日
		// date = c.get(Calendar.DATE);
		// System.out.println(year + "年" + (month + 1) + "月" + date + "日");
 
		// 5年后的10天前
		c.add(Calendar.YEAR, 5);
		c.add(Calendar.DATE, -10);
		// 获取年
		year = c.get(Calendar.YEAR);
		// 获取月
		month = c.get(Calendar.MONTH);
		// 获取日
		date = c.get(Calendar.DATE);
		System.out.println(year + "年" + (month + 1) + "月" + date + "日");
		System.out.println("--------------");
 
		c.set(2011, 11, 11);
		// 获取年
		year = c.get(Calendar.YEAR);
		// 获取月
		month = c.get(Calendar.MONTH);
		// 获取日
		date = c.get(Calendar.DATE);
		System.out.println(year + "年" + (month + 1) + "月" + date + "日");
	}
}

  Get the number of days in February of any year

package day14;
 
 
import java.util.Calendar;
import java.util.Scanner;
 
/*
*  获取任意一年的二月有多少天
 *
 * 分析：
 * 		A:键盘录入任意的年份
 * 		B:设置日历对象的年月日
 * 			年就是A输入的数据
 * 			月是2
 * 			日是1
 * 		C:把时间往前推一天，就是2月的最后一天---计算机的月份是从0开始的--所以2月其实是3月
 * 		D:获取这一天输出即可
 */
public class Lx5 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("请你输入任意年份");
        int year = sc.nextInt();
 
        //设置日历对象的年月日
        Calendar M = Calendar.getInstance();
        //进行年月日的设置
        M.set(year,2,1);
         其实是这一年的3月1日
        //		// 把时间往前推一天，就是2月的最后一天
        // public void add(int field,int amount):根据给定的日历字段和对应的时间，来对当前的日历进行操作。
        M.add(Calendar.DATE,-1);
        //获取这一天输出即可
        //public int get(int field):返回给定日历字段的值。
       System.out.println(M.get(Calendar.DATE));
 
    }
}