shapetr.java

java老师给的java例子很不错

import java.awt.*;
import java.applet.*;
interface Shapes
{
    abstract double getArea();
    abstract double getPerimeter();
}
class Square implements Shapes 
{
	public int x,y;
	public int width,height;
	public double getArea()
        {
            return(width*height); 
        }
        public double getPerimeter()
        {
            return(2*width+2*height); 
        }
        public Square(int x,int y,int width,int height)
	{
           this.x=x;
           this.y=y;
           this.width=width;
           this.height=height;  
        }
}
class Triangle implements Shapes 
{
	public int x,y;
	public int width,height;
	public double c;
        public double getArea()
        {
            return(.5*width*height); 
        }
        public double getPerimeter()
        {
            return(width+height+c); 
        }
        public Triangle(int x,int y,int base,int height)
	{
           this.x=x;
           this.y=y;
           width=base;
           this.height=height;
           c=Math.sqrt(width*width+height*height);  
        }
}	
class Circle implements Shapes 
{
	public int x,y;
	public int width,height;
	public double r;
        public double getArea()
        {
            return(r*r*Math.PI); 
        }
        public double getPerimeter()
        {
            return(2*Math.PI*r); 
        }
        public Circle(int x,int y,int width,int height)
	{
           this.x=x;
           this.y=y;
           this.width=width;
           this.height=height;
           r=(double)width/2.;  
        }
}	

public class ShapeTr extends Applet
{      
       Square Box=new Square(5,15,25,25);
       Triangle Tri=new Triangle(5,50,8,4);
       Circle Oval=new Circle(5,90,25,25);
       public void paint(Graphics g)
       {
		g.drawRect(Box.x,Box.y,Box.width,Box.height);
                g.drawString("Box Area:"+Box.getArea(),50,35);
		g.drawString("Box Perimeter:"+Box.getPerimeter(),50,55);
                g.drawString("Tri Area:"+Tri.getArea(),50,75);
                g.drawString("Tri Perimeter:"+Tri.getPerimeter(),50,95);
		g.drawOval(Oval.x,Oval.y,Oval.width,Oval.height);
                g.drawString("Oval Area:"+Oval.getArea(),50,115);
                g.drawString("Oval Perimeter:"+Oval.getPerimeter(),50,135);	
      } 
}