作业2：声明一个日期类MyDate，包含属性：年、月、日，并在MyDate类中声明几个方法： 1、boolean isLeapYear()：判断当前日期的是闰年吗？ 2、void set(int y, int m, int d)：修改年，月，日为新日期 3、void puls(int years, int months, int days)：加上years年，months月，days天后的日期 并在测试类Test04的main方法中创建对象，并调用测试用JAVA实现完整代码

MyDate.java

public class MyDate {
    private int year;
    private int month;
    private int day;

    public MyDate(int year, int month, int day) {
        this.year = year;
        this.month = month;
        this.day = day;
    }

    public boolean isLeapYear() {
        if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {
            return true;
        }
        return false;
    }

    public void set(int y, int m, int d) {
        year = y;
        month = m;
        day = d;
    }

    public void plus(int years, int months, int days) {
        int y = year + years;
        int m = month + months;
        int d = day + days;

        if (m > 12) {
            y += m / 12;
            m = m % 12;
        }

        if (d > 31) {
            m += d / 31;
            d = d % 31;
        }

        year = y;
        month = m;
        day = d;
    }

    public String toString() {
        return String.format("%04d-%02d-%02d", year, month, day);
    }
}

Test04.java

public class Test04 {
    public static void main(String[] args) {
        MyDate date1 = new MyDate(2020, 2, 29);
        System.out.println(date1.isLeapYear()); //true

        MyDate date2 = new MyDate(2021, 2, 28);
        System.out.println(date2.isLeapYear()); //false

        MyDate date3 = new MyDate(2020, 12, 31);
        date3.plus(1, 1, 1);
        System.out.println(date3); // 2022-02-01

        MyDate date4 = new MyDate(2000, 2, 28);
        date4.plus(4, 6, 30);
        System.out.println(date4); // 2004-09-28
    }
}