0

(私は Java を初めて使用するので、答えをあまりにも混乱させないでください!!!! :P.) Eclipse を使用してゲームを作成したばかりで、本当に楽しいゲームを作りたかったのです! これを作成するのに役立ついくつかのチュートリアルを見落としました。問題は、ゲーム内で移動できないことです。助けていただければ幸いです。私のゲームで wasd を使用して移動しようとしたときに受け取ったエラーは次のとおりです。

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
    at StickFireBasic.KeyAdapt.keyReleased(KeyAdapt.java:19)
    at java.awt.Component.processKeyEvent(Unknown Source)
    at javax.swing.JComponent.processKeyEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
    at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$000(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.awt.EventQueue$4.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)
My class files are: Main, GameFrame, Entity, Player , KeyAdapt.

主要：

package StickFireBasic;

import javax.swing.JFrame;

public class Main {
    public static void main(String[] args) {
        JFrame frame = new JFrame("StickFire");
        frame.setSize(800, 600);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
        frame.setResizable(true);
        frame.add(new GameFrame());
        frame.setVisible(true);
    }

}

ゲームフレーム:

package StickFireBasic;

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JPanel;
import javax.swing.Timer;

public class GameFrame  extends JPanel implements ActionListener{
    
    Timer mainTimer;
    Player player;
    
    public GameFrame() {
        setFocusable(true);
        
        player = new Player(400, 300);
        addKeyListener(new KeyAdapt(player));
        mainTimer = new Timer(10, this);
        mainTimer.start();
    }
    
    public void paint(Graphics g) {
        super.paint(g);
        Graphics2D g2d = (Graphics2D) g;
        player.draw(g2d);

    }
    
    @Override
    public void actionPerformed(ActionEvent arg0) {
        player.update();
        repaint();
    }
}

実在物：

package StickFireBasic;

import java.awt.Graphics2D;

public class Entity {
    
    int x, y;
    
    public Entity(int x, int y) {
        this.x = x;
        this.y = y;
    }
    
    public void update() {
        
    }

    public void draw(Graphics2D g2d) {
        
    }
}

プレーヤー：

package StickFireBasic;

import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.event.KeyEvent;

import javax.swing.ImageIcon;

public class Player extends Entity{
    
    int velX = 0, velY = 0;

    public Player(int x, int y) {
        super(x, y);
        
    }
    
    public void update() {
        y += velY;
        x += velX;
    }
    
    public void draw(Graphics2D g2d) {
        g2d.drawImage(getPlayerImg(), x, y, null);
    }
    
    public Image getPlayerImg() {
        
        
        ImageIcon ic = new ImageIcon("C:/img/stickguy.png/");
        return ic.getImage();
    }
    
    public void keyPressed(KeyEvent e) {
        int key = e.getKeyCode();
        
        if (key == KeyEvent.VK_W) {
            velY = -2;
        } else if (key == KeyEvent.VK_S) {
            velY = 2;
        } else if (key == KeyEvent.VK_A) {
            velX = -2;
        } else if (key == KeyEvent.VK_D) {
            velX = 2;
        }
        
    }
    
    public void keyReleased(KeyEvent e) {
        int key = e.getKeyCode();
        
        if (key == KeyEvent.VK_W) {
            velY = 0;
        } else if (key == KeyEvent.VK_S) {
            velY = 0;
        } else if (key == KeyEvent.VK_A) {
            velX = 0;
        } else if (key == KeyEvent.VK_D) {
            velX = 0;
        }
        
    }

}

キー適応:

package StickFireBasic;

import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;

public class KeyAdapt  extends KeyAdapter {
    
    Player p;
    
    public KeyAdapt(Player player) {
        
    }
    
    public void keyPressed(KeyEvent e) {
        p.keyPressed(e);
    }
    
    public void keyReleased(KeyEvent e) {
        p.keyReleased(e);
    }

}
4

1 に答える 1

0

まあ、これは私には間違っているように見えます：

Player p;

public KeyAdapt(Player player) {

}

pどこかに値を割り当てるべきではありませんか？コンストラクターのように？現在、コンストラクターパラメーターを完全に無視しています。

それ以外の場合は、常にnull値になります。したがって、ハンドラーで逆参照すると、がスローされますNullPointerException。また、わかりやすくするために名前を変更し、クラス自体の名前を変更し、プライベートで最終的なものにする必要があります。

public class PlayerKeyAdapter extends KeyAdapter {
    private final Player player;

    public PlayerKeyAdapter(Player player) {
        this.player = player;
    }

    public void keyPressed(KeyEvent e) {
        player.keyPressed(e);
    }

    public void keyReleased(KeyEvent e) {
        player.keyReleased(e);
    }
}
于 2012-07-23T15:29:06.367 に答える