如何使用键绑定使矩形在屏幕上移动？

我试图创建的游戏是贪吃蛇，到目前为止我已经弄清楚如何使用paint(Graphics g)一点JPanel、鼠标侦听器，现在我正在尝试创建一个将在屏幕上移动并使用键绑定或键侦听器的矩形，但我不知道应该如何处理此问题。

这是到目前为止我的代码，它有两部分。 第一部分称为snake2因为如果我不知道自己在做什么，我就会用不同的东西制作相同的程序。Snake使用框架，但是Snake2 uses JPanel（看起来好多了……）

    import java.awt.*;

    //required for MouseListener
    import java.awt.event.*;

    //requied for Graohics
    import java.applet.*;
    import javax.swing.*;

    public class Snake2 extends JPanel
    {
      private Rectangle sampleObject;

      public Snake2()
      {
         addMouseListener(new MouseListener());

      }


      /* create background */
      public void paint (Graphics g)
      {
        Font angel = new Font("Angelic War", Font.BOLD, 60);
        Font ith = new Font("Ithornît", Font.BOLD, 78);

        setBackground(Color.darkGray);
        g.setColor(Color.darkGray);
        g.fillRect(0,0,700,850);
        g.setColor(Color.gray);
        g.fillRect(50,150,600,650);
        g.setColor(Color.white);
        g.drawRect(50,150,600,650);

        g.drawString("Quit",52,116);
        g.drawRect(50,100,30,20);

        //g.setFont(angel);
        //g.drawString("SNAKE",300,70);
        g.setFont(ith);
        g.drawString("SNAKE",280,90);  
      }

      public void sprite (int x, int y, Graphics g){
        g.setColor(Color.white);
        g.fillRect(300,200,10,10);
      }

      public void start (int x, int y, Graphics g){
        g.setColor(Color.white);
        g.drawString("START GAME",300,425);
      }
    }


    /* Tracks where mouse is clicked */
    class MouseListener extends MouseAdapter
    {
      public void mouseReleased(MouseEvent me)
      {
        if (me.getX() >= 50 && me.getX() <= 80 && me.getY() >= 100 && me.getY() <= 120)
        {
          System.exit(0);
        }

          String str="Mouse Released at "+me.getX()+","+me.getY();
          System.out.println(str);
      }
    }

第二部分是：

    import javax.swing.JFrame;
    import java.awt.Dimension;

    public class SnakeDisplay
    {

      public static void main ( String [ ] arguments )
      {   
        JFrame frame = new JFrame ( "Snake" );
        Snake2 panel = new Snake2 ( );


        frame.setDefaultCloseOperation ( JFrame.EXIT_ON_CLOSE );
        frame.add ( panel );
        frame.setContentPane ( panel );

        frame.setPreferredSize ( new Dimension ( 700, 850 ) );
        //frame.setLocationRelativeTo ( null );
        frame.setVisible ( true );
        frame.pack ( );     
      }
    }

1. 你应该覆盖paintComponent在你的JPanel并打电话super.paintComponent(g) in it.
2. See 如何使用按键绑定教程 http://docs.oracle.com/javase/tutorial/uiswing/misc/keybinding.html。在这种情况下，首选键绑定而不是KeyListener
3. pack() then setVisible()
4. 您应该为 x 和 y 位置设置全局变量，以便可以从您的内部访问它们Action。然后在您的操作中，增加您的 x 或 y 并重新绘制

尝试运行这个例子

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class KeyBidings extends JFrame {
    int x = 0;
    int y = 0;

    DrawPanel drawPanel = new DrawPanel();

    public KeyBidings(){
        Action rightAction = new AbstractAction(){
            public void actionPerformed(ActionEvent e) {
                x +=10;
                drawPanel.repaint();
            }
        };

            InputMap inputMap = drawPanel.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW);
            ActionMap actionMap = drawPanel.getActionMap();

        inputMap.put(KeyStroke.getKeyStroke("RIGHT"), "rightAction");
        actionMap.put("rightAction", rightAction);

        add(drawPanel);

        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setLocationRelativeTo(null);
        setVisible(true);
    }

    private class DrawPanel extends JPanel {


        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.setColor(Color.GRAY);
                    g.fillRect(0, 0, getWidth(), getHeight());
            g.setColor(Color.GREEN);
            g.fillRect(x, y, 50, 50);
        }

        public Dimension getPreferredSize() {
            return new Dimension(400, 200);
        }
    }

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable(){
            public void run(){
                new KeyBidings();
            }
        });
    }
}

这是您更关心的代码

    Action rightAction = new AbstractAction(){
        public void actionPerformed(ActionEvent e) {
            x +=10;
            drawPanel.repaint();
        }
    };

    InputMap inputMap = drawPanel.getInputMap(JPanel.WHEN_IN_FOCUSED_WINDOW);
    ActionMap actionMap = drawPanel.getActionMap();

    inputMap.put(KeyStroke.getKeyStroke("RIGHT"), "rightAction");
    actionMap.put("rightAction", rightAction);

创建自定义操作并将该操作添加到链接到输入映射击键的操作映射。在操作中，只需根据方向增加或减少 x 和/或 y，然后重新绘制面板。

See 按键绑定教程 http://docs.oracle.com/javase/tutorial/uiswing/misc/keybinding.html | 图形教程 http://docs.oracle.com/javase/tutorial/2d/