java - 图像不动

Question

我的图像不动。
这是应用程序的完整代码:

package Game;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Game extends JPanel {

    private static final long serialVersionUID = 1L;

    private BufferedImage image;

    public static final int WIDTH = 600;
    public static final int HEIGHT = 500;
    private int x = 1;
    private int y = 1;

    private static int dx;
    private static int dy;

    private boolean leftPressed = false;
    private boolean rightPressed = false;
    private boolean topPressed = false;
    private boolean downPressed = false;

    public static void main(String avg[]) throws IOException {
        Game abc = new Game();

    }

    public Game() {
        try {
            JFrame frame = new JFrame();
            image = ImageIO.read(new File(
                    "C:\\Users\\дНМ\\workspace\\Game\\image\\heroG.png"));

            frame.setSize(WIDTH, HEIGHT);
            frame.setVisible(true);
            frame.getContentPane().add(this);
            this.setBackground(Color.BLACK);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.setTitle("Tittle - Game");
            addKeyListener(new KeyInputHandler());
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }



    public void move() {

        x += dx;
        y += dy;

        if (x < 1) {
            x = 1;
        }

        if (y < 1) {
            y = 1;
        }
    }

    public void update(long delta) {
        if (leftPressed == true) {
            x--;
        }
        if (rightPressed == true) {
            x++;
        }
    }

    public void update2(long delta) {
        if (downPressed == true) {
            y--;
        }
        if (topPressed == true) {
            y++;
        }
    }

    private class KeyInputHandler extends KeyAdapter {
        public void keyPressed(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_LEFT) {
                leftPressed = true;
                dx = -1;
            }
            if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
                rightPressed = true;
                dx = 1;
            }
            if (e.getKeyCode() == KeyEvent.VK_UP) {
                topPressed = true;
                dy = -1;
            }
            if (e.getKeyCode() == KeyEvent.VK_DOWN) {
                downPressed = true;
                dy = 1;
            }
        }

        public void keyReleased(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_LEFT) {
                leftPressed = false;
                dx = 0;
            }
            if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
                rightPressed = false;
                dx = 0;
            }
            if (e.getKeyCode() == KeyEvent.VK_UP) {
                topPressed = false;
                dy = 0;
            }
            if (e.getKeyCode() == KeyEvent.VK_DOWN) {
                downPressed = false;
                dy = 0;
            }
        }
    }
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, x, y, null); 
    }
}

这是怎么回事？
请指出您可能需要添加的错误。

Answer 1

首先:您的面板未拦截关键事件，请检查其他问题，例如:addKeyListener() doesn't work for JPanel

第二:按下按键时更改变量 dx 和 dy，但没有调用 move() 方法

第三按下每个键后您不会重新绘制。

这些是修改:

游戏构造函数

public Game() {
    try {
        JFrame frame = new JFrame();
        image = ImageIO.read(new File("Zombatar.jpg"));

        frame.setSize(WIDTH, HEIGHT);
        frame.setVisible(true);
        frame.getContentPane().add(this);
        this.setBackground(Color.BLACK);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setTitle("Tittle - Game");

        addKeyListener(new KeyInputHandler());

        //this is important to intercept key events
        setFocusable(true);
        requestFocusInWindow();

    } catch (IOException ex) {
        ex.printStackTrace();
    }
}

KeyAdapter

private class KeyInputHandler extends KeyAdapter {

    public void keyPressed(KeyEvent e) {
        if (e.getKeyCode() == KeyEvent.VK_LEFT) {
            dx = -1;
        }
        else if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
            dx = 1;
        }
        else if (e.getKeyCode() == KeyEvent.VK_UP) {
            dy = -1;
        }
        else if (e.getKeyCode() == KeyEvent.VK_DOWN) {
            dy = 1;
        }

        //first call move to update x and y and later repaint tha JPanel
        move();
        repaint();
    }
}