randomlybouncingballs.java

书籍"Java_面向事件编程"的附带光盘代码

import java.awt.*;
import objectdraw.*;

// A class to draw a bunch of basketballs on the screen so
// that by clicking we can watch them bounce randomly
public class RandomlyBouncingBalls extends WindowController
{
    
    // all the balls displayed.
    private BallCollection allTheBalls;
    
    // create the balls as soon as the program starts
    public void begin()
    {
        allTheBalls = new BallCollection( canvas );
    }
    
    // create an active object to bounce them when clicked.
    public void onMouseClick( Location point )
    {
        new Bouncer( allTheBalls );
    }
    
    // hide all the balls when the mouse leaves
    public void onMouseExit( Location point )
    {
        allTheBalls.hide();
    }
    
    // show all the balls when the mouse arrives
    public void onMouseEnter( Location point )
    {
        allTheBalls.show();
    }
    
    
}