hw4_819.java

创建一些形状类

import java.applet.Applet;
import java.awt.Graphics;

// create a new applet class
public class hw4_819 extends Applet
{
    private static final int NUM_OF_SHAPES = 5;

    int width, height;

    MyLine line[]      = new MyLine[NUM_OF_SHAPES];
    MyRect rectangle[] = new MyRect[NUM_OF_SHAPES];
    MyOval oval[]      = new MyOval[NUM_OF_SHAPES];

    public void init()
    {
	width  = getSize().width;
	height = getSize().height;
    }

    public void start()
    {
	int x, y;
	
	for (int i = 0; i < NUM_OF_SHAPES; i++) {
	    line[i] = new MyLine( (int) (Math.random()*width)+1,
				  (int) (Math.random()*height)+1,
				  (int) (Math.random()*width)+1,
				  (int) (Math.random()*height)+1);

	    x = (int) (Math.random()*width)  + 1;
	    y = (int) (Math.random()*height) + 1;
	    rectangle[i] = new MyRect( x,
				       y,
				       (int)(Math.random()*(width-x-1))+1,
				       (int)(Math.random()*(height-y-1))+1);
	    
	    x = (int) (Math.random()*width)  + 1;
	    y = (int) (Math.random()*height) + 1;
	    oval[i] = new MyOval( x,
				  y,
				  (int)(Math.random()*(width-x-1))+1,
				  (int)(Math.random()*(height-y-1))+1);
	}
    }

    // override the default null paint method
    public void paint(Graphics g)
    {
	for (int i = 0; i < line.length; i++)
	    line[i].draw(g);

	for (int i = 0; i < rectangle.length; i++)
	    rectangle[i].draw(g);

	for (int i = 0; i < oval.length; i++)
	    oval[i].draw(g);
    }
}