JDK8之前：Calendar类(抽象类)日历的使用

import java.util.Calendar;
import java.util.Date;

/**
 *Calendar类(抽象类)日历的使用
 *
 * @author fu jingchao
 * @creat 2021/11/7-17:10
 */
public class CalendarTest {
    public static void main(String[] args) {
        //1.实例化
        //方式一：创建其子类(GregorianCalendar)的对象
        //方式二：调用其静态方法getInstance()
        Calendar calendar = Calendar.getInstance();
        System.out.println(calendar.getClass());//class java.util.GregorianCalendar

        //2.常用方法
        //1.get()
        int days = calendar.get(Calendar.DAY_OF_MONTH);
        System.out.println(days);
        System.out.println(calendar.get(Calendar.DAY_OF_WEEK));

        //2.set()
        calendar.set(Calendar.DAY_OF_MONTH,22);
        days = calendar.get(Calendar.DAY_OF_MONTH);
        System.out.println(days);

        //3.add()
        calendar.add(Calendar.DAY_OF_MONTH,3);//如果是负数，就是减几天
        days = calendar.get(Calendar.DAY_OF_MONTH);
        System.out.println(days);

        //4.getTime():日历类---->Date
        Date date = calendar.getTime();
        System.out.println(date);//Sat Dec 25 16:58:11 CST 2021

        //5.setTime():Date---->日历类
        Date date1 = new Date();
        calendar.setTime(date1);
        days = calendar.get(Calendar.DAY_OF_MONTH);
        System.out.println(days);

        System.out.println(calendar.get(Calendar.MONTH));//注意：获取月份时，一月是0.二月是1，...，12月是11

    }

}