inherit.java

java老师给的java例子很不错

class Shape								//定义父类Shape
{
	protected int lineSize;				//线宽

	public Shape()						//构造方法1
	{
		lineSize = 1;
	}

	public Shape(int ls)				//构造方法2
	{
		lineSize = ls;
	}

	public void setLineSize(int ls)		//设置线宽
	{
		lineSize = ls;
	}

	public int getLineSize()			//获得线宽
	{
		return lineSize;
	}
	
	public void draw()					//画图
	{
		System.out.println("Draw a Shape");
	}
}

class Ellipse extends Shape				//定义子类Ellipse
{
	private int centerX;				//圆心X坐标
	private int centerY;				//圆心Y坐标
	private int width;					//椭圆宽度
	private int height;					//椭圆高度

	public Ellipse(int x, int y, int w, int h) 	//构造方法
	{
		super();						//调用父类的构造方法1
		centerX = x;
		centerY = y;
		width = w;
		height = h;
	}

	public void draw()					//覆盖父类的draw()方法
	{
		System.out.println("draw a Ellipse");
	}
}

class Rectangle extends Shape			//定义子类Rectangle
{
	private int left;					//矩形左上角X坐标
	private int top;					//矩形左上角Y坐标
	private int width;					//矩形长度
	private int height;					//矩形宽度

	public Rectangle(int l, int t, int w, int h)	//构造方法
	{
		super(2);						//调用父类的构造方法2
		left = l;
		top = t;
		width = w;
		height = h;
	}

	public void draw()					//覆盖父类的draw()方法
	{
		System.out.println("draw a Rectangle");
	}
}

public class Inherit					//定义类Inherit
{
	public static void main(String args[])
   	{
		Ellipse ellipse = new Ellipse(30, 30, 50,60); 
//创建子类Ellipse的对象
		ellipse.setLineSize(2);	
//调用父类方法重新设置lineSize 值为2
		System.out.println("LineSize of ellipse : " + 
ellipse.getLineSize());

		Rectangle rectangle = new Rectangle(0, 0, 20, 30); 
//创建子类rectangle对象
		rectangle.setLineSize(3); 
//调用父类方法重新设置lineSize属性为3
		System.out.println("LineSize of rectangle : " + 
rectangle.getLineSize());
		ellipse.draw();					//访问子类方法
		rectangle.draw();				//访问子类方法
	}
 }