Java教程例题3.2

1.用来体验下封装性

2.代码：

public class MyDate//类声明 
{
	//成员变量
	private int year,month,day;
	private static int thisYear;
	static 
	{
		thisYear=2009;
	}
	/*---------------------------设置对象属性的方法----------------------------------------------*/
	void set(int year,int month,int day)//成员方法，设置日期值
	{
		this.year=year;
		this.month=(month>=1&&month<=12)?month:1;
		this.day=(day>=1&&day<=31)?day:1;//这其实不一定能保证日期合法，比如二月的情况
	}
	void set(MyDate d)
	{
		set(d.year,d.month,d.day);
	}
	/*------------------------------------------------------------------------------------------*/
	/*----------------------------构造方法-------------------------------------------------------*/
	public MyDate(int year,int month,int day)
	{
		this.set(year,month,day);
	}
	public MyDate()
	{
		this(1970,1,1);
	}
	public MyDate(MyDate d)
	{
		this.set(d);
	}
	/*-------------------------------------------------------------------------------------------*/
	/*-------------------------------获得对象属性的方法-------------------------------------------*/
	public int getYear()
	{
		return this.year;//
	}
	public int getMonth()
	{
		return this.month;
	}
	public int getDay()
	{
		return this.day;
	}
	public static int getThisYear()
	{
		return thisYear;
	}
	/*-------------------------------------------------------------------------------------------*/
	/*-----------------------------------把类转化为字符串-----------------------------------------*/
	public String toString()
	{
		return year+"年"+month+"月"+day+"日";
	}
	/*-------------------------------------------------------------------------------------------*/
	/*-------------------------------------判断闰年----------------------------------------------*/
	public static boolean isLeapYear(int year)
	{
		return year%400==0||year%4==0&&year%100!=0;
	}
	public boolean isLeapYear()
	{
		return isLeapYear(this.year);//调用静态方法
	}
	/*-------------------------------------------------------------------------------------------*/
	/*------------------------------------判断日期是否相等--------------------------------------------*/
	public boolean equals(MyDate d)
	{
		return this==d||d!=null&&d.year==year&&d.month==month&&d.day==day;//this指代调用本方法的当前对象
	}
	/*-------------------------------------------------------------------------------------------*/
	/*--------------------------------返回当月的天数-----------------------------------------*/
	public static int daysOfMonth(int year,int month)
	{
		switch(month)//
		{
			case 1:return 31;
			case 3:return 31;
			case 5:return 31;
			case 7:return 31;
			case 8:return 31;
			case 10:return 31;
			case 12: return 31;
			case 4:case 6:case 9:case 11:return 30;
			case 2:return isLeapYear(year)?29:28;
			default: return 0;
		}
	}
	public int daysOfMonth()
	{
		return daysOfMonth(this.year,this.month);
	}
	/*---------------------------------改为第二天的日期----------------------------------------------*/
	public void tomorrow()
	{
		this.day++;
		if(day>this.daysOfMonth())
		{
			day=1;
			month++;
			if(month>12)
			{
				month=1;
				year++;
			}
		}
	}
	/*-------------------------------------------------------------------------------------------*/
	/*----------------------------------返回前一天的日期--------------------------------------------*/
	public MyDate yestoday()
	{
		MyDate yes=new MyDate(this);
		yes.day--;
		if(yes.day==0)
		{
			yes.month--;
			if(yes.month==0)
			{
				yes.year--;
				yes.month=12;
			}
			yes.day=daysOfMonth(yes.year,yes.month);
		}
		return yes;
	}
	/*-------------------------------------------------------------------------------------------*/	
	/*public static void main(String args[])
	{
		System.out.println("今年是"+MyDate.getThisYear()+", 闰年? "+MyDate.isLeapYear(MyDate.getThisYear()));
		MyDate d1=new MyDate(2008,8,8);
		MyDate d2=new MyDate(d1);
		System.out.println(d2+", 闰年? "+d2.isLeapYear());
		System.out.print(d2+" 的昨天是 "+d2.yestoday()+"\n"+d2+" 的明天是 ");
		d2.tomorrow();
		System.out.println(d2);
	}*/
}

class MyDate_ex
{
	public static void main(String args[])
	{
		System.out.println("今年是"+MyDate.getThisYear()+", 闰年? "+MyDate.isLeapYear(MyDate.getThisYear()));
		MyDate d1=new MyDate(2008,8,8);
		MyDate d2=new MyDate(d1);
		System.out.println(d2+", 闰年? "+d2.isLeapYear());
		System.out.print(d2+" 的昨天是 "+d2.yestoday()+"\n"+d2+" 的明天是 ");
		d2.tomorrow();
		System.out.println(d2);
	}
}