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我想编写一个程序,用户可以通过按WASD键在窗口上移动球。然而,当用户按下按键时,什么都不会发生。贝娄是我的程序代码,任何人都可以告诉我什么是错的,或者我该如何改进我的程序? (如果我删除的KeyListener,并把super.x ++球可以移动;在ball.move())Java GUI:如何使用WASD键移动球?
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import javax.swing.JApplet;
import javax.swing.JComponent;
import java.awt.geom.*;
public class MoveBall extends JApplet
{
public final int Width = 567;
public final int Height = 567;
public static PaintSurface canvas;
public void init()
{
canvas = new PaintSurface();
this.setSize(Width, Height);
this.add(canvas, BorderLayout.CENTER);
ScheduledThreadPoolExecutor executor = new ScheduledThreadPoolExecutor(3);
executor.scheduleAtFixedRate(new Action(), 0L, 10L, TimeUnit.MILLISECONDS);
}
}
class Action implements Runnable
{
public void run()
{
MoveBall.canvas.repaint();
}
}
class PaintSurface extends JComponent
{
Ball ball = new Ball(20);
public PaintSurface()
{
addKeyListener(new Listener());
}
public void paint(Graphics g)
{
Graphics2D g2 = (Graphics2D)g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
ball.move();
g2.setColor(Color.GREEN);
g2.fill(ball);
g2.setColor(Color.BLACK);
g2.drawString("W,A,S,D or arrow keys to move", 7, 17);
}
}
class Ball extends Ellipse2D.Float
{
public int xspeed, yspeed;
public Ball(int d)
{
super(370,370, d,d);
}
public void move()
{
if(super.x >567)
super.x -=567;
if(super.x <0)
super.x +=567;
if(super.y >567)
super.y -=567;
if(super.y < 0)
super.y +=567;
super.x += xspeed ;
super.y += yspeed ;
}
}
class Listener implements KeyListener
{
public void keyPressed(KeyEvent ev)
{
if(ev.getKeyCode() == KeyEvent.VK_W)
{
MoveBall.canvas.ball.xspeed = 0 ;
MoveBall.canvas.ball.yspeed = -1 ;
}
if(ev.getKeyCode() == KeyEvent.VK_A)
{
MoveBall.canvas.ball.xspeed = -1 ;
MoveBall.canvas.ball.yspeed = 0 ;
}
if(ev.getKeyCode() == KeyEvent.VK_S)
{
MoveBall.canvas.ball.xspeed = 0 ;
MoveBall.canvas.ball.yspeed = 1 ;
}
if(ev.getKeyCode() == KeyEvent.VK_D)
{
MoveBall.canvas.ball.xspeed = 1 ;
MoveBall.canvas.ball.yspeed = 0 ;
}
}
public void keyReleased(KeyEvent arg0){}
public void keyTyped(KeyEvent arg0){}
}