将图形添加到 KeyListener 的并发症

Question

我正在尝试将射击添加到我的游戏中，但我无法将我的 Player 类更改为抽象类，否则它将无法正常工作，因此我只能做我能做的事情。

我已经尝试了一百万种不同的方法来解决这个问题，但都没有奏效。我搜索并搜索并观看了视频教程无济于事。这是我最后的选择，我相信有人可以帮助我。

这是我的第一个小程序，但我对 java 并不陌生。这不是 2D 游戏。这只是我一直在做的一个基本实验。

MainClass.java

/**
 *
 * @author Alexander Benoit
 */
import java.applet.*;
import java.awt.*;

public class MainClass extends Applet implements Runnable {

    private static final long serialVersionUID = 1L;
    Thread thread = new Thread(this);
    boolean running = true;
    Player p;
    Enemy e;
    Image dbImage;
    Graphics dbg;
    int xpos;
    int ypos;
    int mousex;
    int mousey;

    @Override
    public void init() {
        setSize(400, 400);
        p = new Player(this);
        e = new Enemy(this);
    }

    @Override
    public void start() {
        thread.start();
    }

    @Override
    public void destroy() {
        running = false;
    }

    @Override
    public void stop() {
        running = false;
    }


    @Override
    public void run() {
        while (running) {
            repaint();
            p.update(this);
            e.update(this, p);
            try {
                Thread.sleep(20);
            } catch (InterruptedException e) {
                System.out.print("Error occured");
            }
        }

    }

    @Override
    public void update(Graphics g) {
        dbImage = createImage(getWidth(), getHeight());
        dbg = dbImage.getGraphics();
        paint(dbg);
        g.drawImage(dbImage, 0, 0, this);
    }

    @Override
    public void paint(Graphics g) {
        g.drawString("Game", 180, 20);
        p.paint(g, this);
        e.paint(g, this);
    }
}

Player.java

/**
 *
 * @author Alexander Benoit
 */
import java.awt.*;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.net.URL;

public class Player implements KeyListener {

    private int x = 200, y = 200, velX = 0, velY = 0;
    private URL url;
    private Image player;
    private Image playerimg;
    private Image Image;
    public boolean isShooting;


    public Player(MainClass mc) {
        url = mc.getDocumentBase();
        player = mc.getImage(url, "http://i563.photobucket.com/albums/ss75/belhelmiel/player-1.png");
    }

    public void update(MainClass mc) {
        mc.addKeyListener(this);
        x += velX;
        y += velY;
    }

    public void paint(Graphics g, MainClass mc) {
        g.drawImage(player, x, y, mc);
        g.drawString("X:" + x + " Y:" + y, 10, 10);
        //g.drawRect(x, y, 50, 50);
    }

    @Override
    public void keyTyped(KeyEvent e) {
        //throw new UnsupportedOperationException("Not supported yet.");
    }


    @Override
    public void keyPressed(KeyEvent e) {
        switch (e.getKeyCode()) {

            case KeyEvent.VK_SPACE: {
                //This should make the player start shooting
                //I've tried a million different things
                //each one gave me some kind of problem primarily
                //because I can't set this class to abstract
                break;
            }

            case KeyEvent.VK_RIGHT: {
                if (x >= 430) {
                    x = -40;
                }
                velX = 2;
                break;
            }
            case KeyEvent.VK_LEFT: {
                if (x <= -40) {
                    x = 430;
                }
                velX = -2;
                break;
            }
            case KeyEvent.VK_UP: {
                if (y <= -35) {
                    y = 430;
                }
                velY = -2;
                break;
            }
            case KeyEvent.VK_DOWN: {
                if (y >= 400) {
                    y = -30;
                }
                velY = 2;
                break;
            }
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        switch (e.getKeyCode()) {
            case KeyEvent.VK_SPACE: {
                //This should make the player stop shooting
                break;
            }

            case KeyEvent.VK_RIGHT: {
                velX = 0;
                break;
            }
            case KeyEvent.VK_LEFT: {
                velX = 0;
                break;
            }
            case KeyEvent.VK_UP: {
                velY = 0;
                break;
            }
            case KeyEvent.VK_DOWN: {
                velY = 0;
                break;
            }
        }
    }

    public int getX() {
        return x;
    }

    public int getY() {
        return y;
    }

    void restart() {
        x = 200 - 38 / 2;
        y = 200 - 38 / 2;
    }
}

Enemy.java

import java.awt.Graphics;
import java.awt.Image;
import java.net.URL;

/**
 *
 * @author Alexander Benoit
 */
public class Enemy {

    private int x = 50, y = 50, Speed=3;
    private URL url;
    private Image enemy;

    public Enemy(MainClass mc) {
        url = mc.getDocumentBase();
        enemy = mc.getImage(url, "http://i563.photobucket.com/albums/ss75/belhelmiel/enemy.png");
    }

    public void update(MainClass mc, Player p) {
        x+=Speed;
        if(x<=0){
            Speed=3;
        }else if(x>=mc.getWidth()-33){
            Speed=-3;
        }

        Collision(p);
    }

    public void paint(Graphics g, MainClass mc) {
        g.drawImage(enemy, x, y, mc);
    }

    private void Collision(Player p) {
        int PX = p.getX();
        int PY = p.getY();

        if(PX-38 <= x && PX+38 >= x && PY-38 <= y && PY+38 >= y) {
            p.restart();
            System.out.print("Collision Detected");
        }
    }
}

很抱歉，如果我不能为您提供足够的信息，我自己也很缺乏，因为在尝试了很长时间之后，我在网上找不到任何有用的信息。

总结： 当玩家按住空格键时，我需要发射某种子弹。我知道如何使用 keylistener，但是如果不将我的 Player 类设置为抽象，我就不能将 keylistener 与“Graphics g”一起使用，这是我做不到的，或者我的游戏将无法运行。我一直在寻找，试图弄清楚如何做到这一点，但无济于事。抱歉，如果这看起来有点奇怪，我重新启动可能会更好，但我已经为此工作了几个小时。

Answer 1

您绝对可以在不将播放器类设置为抽象的情况下使用 keylistener 和图形。您只需要实现接口中声明的所有方法。你可以了解抽象类here和AWT/Swing绘画here。