（SafeIcon）为什么（icon）.getIconWidth（）;返回null？

时间：2015-12-08 19:24:17

标签： java jframe icons bufferedimage

我正在编写一个游戏，我现在正在努力的是玩家旋转但没有成功。下面是错误信息：

Exception in thread "Thread-2" java.lang.NullPointerException
at Schoo.NewGame.SafeIcon.getIconWidth(SafeIcon.java:29)
at Schoo.NewGame.TheRealGame.turn(TheRealGame.java:412)
at Schoo.NewGame.TheRealGame.turnPlayer(TheRealGame.java:427)
at Schoo.NewGame.TheRealGame.RepaintPlayer(TheRealGame.java:377)
at Schoo.NewGame.TheRealGame$2.run(TheRealGame.java:225)
at java.lang.Thread.run(Unknown Source)

SafeIcon中的第29行：

return wrappee.getIconHeight();

更多内容：

private Icon wrappee;
    private Icon standIn;

    public SafeIcon(Icon icon) {
        wrappee = icon;
    }

    @Override
    public int getIconHeight() {
        return wrappee.getIconHeight();
    }

    @Override
    public int getIconWidth() {
        return wrappee.getIconWidth();
    }

TheRealGame中的第412行：

BufferedImage bi = new BufferedImage(icon.getIconWidth(), icon.getIconHeight(), BufferedImage.TYPE_INT_RGB);

更多内容：

Icon icon;
public void turn(Direction d){
    if (pt == Playere.Kaneki){
        icon = new SafeIcon(playerImage.getIcon());
        BufferedImage bi = new BufferedImage(icon.getIconWidth(), icon.getIconHeight(), BufferedImage.TYPE_INT_RGB);
        Graphics2D g = (Graphics2D) bi.getGraphics();
        if (d == Direction.LEFT && p.getDirection() == Direction.UP){
            g.rotate(Math.PI / 2, playerImage.getWidth(), playerImage.getHeight());
            playerImage.getIcon().paintIcon(null, g, 0, 0);
            g.dispose();
        }
    }
    if (pt == Playere.Touka){

    }
}

这是我找到safeIcon的地方。 如果你需要我的整个主要课程：

public class TheRealGame{

private static Bullets b = new Bullets();
private static boolean running = false;
private static boolean paused = false;
private static boolean right = false, left = false, up = false, down = false;
private static JFrame f;
private static ArrayList<JLabel> ae = new ArrayList<JLabel>();
private static Player p;
private static Playere pt;
private static JLabel playerImage;
private static Icon playerIcon;
private static ImageIcon imageIcon;
private static boolean attacking = false;
private static boolean info = false;
private static JLabel iy, ix, im, in, iu;
private static Enemys enemys = new Enemys();
private static ArrayList<JLabel> bullets = new ArrayList<JLabel>();

public static void main(Playere playertype){
    pt = playertype;
    p = new Player(pt);
    f = new JFrame();
    f.setVisible(true);
    f.setSize(700, 700);
    f.setResizable(false);
    f.setLocationRelativeTo(null);
    f.addKeyListener(new KeyListener(){
        @Override
        public void keyPressed(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_UP || e.getKeyChar() == KeyEvent.VK_W){
                up = true;
            }
            if (e.getKeyCode() == KeyEvent.VK_LEFT || e.getKeyChar() == KeyEvent.VK_A){
                left = true;
            }
            if (e.getKeyCode() == KeyEvent.VK_DOWN || e.getKeyChar() == KeyEvent.VK_S){
                down = true;
            }
            if (e.getKeyCode() == KeyEvent.VK_RIGHT || e.getKeyChar() == KeyEvent.VK_D){
                right = true;
            }
            if (e.getKeyCode() == KeyEvent.VK_SPACE || e.getKeyCode() == KeyEvent.VK_ENTER){
                if (attacking == false){
                    p.attack();
                }
            }
            if (e.getKeyCode() == KeyEvent.VK_F3){
                if (info == true){
                    info = false;
                    iy.setVisible(false);
                    ix.setVisible(false);
                    im.setVisible(false);
                    in.setVisible(false);
                    iu.setVisible(false);
                }else if (info == false){
                    info = true;
                    iy.setVisible(true);
                    ix.setVisible(true);
                    im.setVisible(true);
                    in.setVisible(true);
                    iu.setVisible(true);
                }
            }
        }

        @Override
        public void keyReleased(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_UP || e.getKeyChar() == KeyEvent.VK_W){
                up = false;
            }
            if (e.getKeyCode() == KeyEvent.VK_LEFT || e.getKeyChar() == KeyEvent.VK_A){
                left = false;
            }
            if (e.getKeyCode() == KeyEvent.VK_DOWN || e.getKeyChar() == KeyEvent.VK_S){
                down = false;
            }
            if (e.getKeyCode() == KeyEvent.VK_RIGHT || e.getKeyChar() == KeyEvent.VK_D){
                right = false;
            }
            if (e.getKeyCode() == KeyEvent.VK_SPACE || e.getKeyCode() == KeyEvent.VK_ENTER){
                if (attacking == true)
                    p.attack();
            }
        }

        @Override
        public void keyTyped(KeyEvent e) {

        }
    });
    playerImage = new JLabel();
    iy = new JLabel();
    ix = new JLabel();
    im = new JLabel();
    in = new JLabel();
    iu = new JLabel();
    iy.setLocation(0, 10);
    ix.setLocation(0, 20);
    im.setLocation(0, 30);
    in.setLocation(0, 40);
    iu.setLocation(0, 50);
    iy.setBounds((int) iy.getLocation().getX(), (int) iy.getLocation().getY(), 100, 15);
    ix.setBounds((int) ix.getLocation().getX(), (int) ix.getLocation().getY(), 100, 15);
    im.setBounds((int) im.getLocation().getX(), (int) im.getLocation().getY(), 100, 15);
    in.setBounds((int) in.getLocation().getX(), (int) in.getLocation().getY(), 100, 15);
    iu.setBounds((int) iu.getLocation().getX(), (int) iu.getLocation().getY(), 300, 15);
    f.add(ix);
    f.add(iy);
    f.add(im);
    f.add(in);
    f.add(iu);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setTitle("free play - tokyo ghoul");
    Start();
    p.Paint();
}
public static void resume(){
    if (paused == false){
        return;
    }
}
public static void pause(){
    if (paused == true){
        return;
    }
}
public static void Stop(){
    if (running == false){
        return;
    }
    running = false;
}
public static void move(JLabel l, int newX, int newY){
    l.setLocation(newX, newY);
    l.repaint();
    f.repaint();
}

public static void remove(JLabel l){
    f.remove(l);
    l.setVisible(false);
}

public static JLabel getPlayerImage(){
    return playerImage;
}

public static Player getPlayer(){
    return p;
}

public static void Start(){
    running = true;

    new Thread(new Runnable(){
        @Override
        public void run() {
            int last = 0, u = 0;
            while (running == true){
                if (paused != true){
                    if (up == true){
                        p.move(p.getX(), p.getY()-1);
                        if (p.getDirection() != Direction.UP)
                            turnPlayer(Direction.UP);
                    }
                    if (down == true){
                        p.move(p.getX(), p.getY()+1);
                        if (p.getDirection() != Direction.DOWN)
                            turnPlayer(Direction.DOWN);
                    }
                    if (left == true){
                        p.move(p.getX()-1, p.getY());
                        if (p.getDirection() != Direction.LEFT)
                            turnPlayer(Direction.LEFT);
                    }
                    if (right == true){
                        p.move(p.getX()+1, p.getY());
                        if (p.getDirection() != Direction.RIGHT)
                            turnPlayer(Direction.RIGHT);
                    }
                    if (info == true){
                        int l = 10-last;
                        iy.setText("y: "+p.getY());
                        ix.setText("x: "+p.getX());
                        im.setText("enemys: "+ae.size());
                        in.setText("next enemy: "+l);
                        iu.setText("Updated "+u+" times.");
                        RefreshInfo();
                    }
                    if (p.getY() >= +334){
                        p.move(p.getX(), +334);
                    }
                    if (p.getY() <= -334){
                        p.move(p.getX(), -334);
                    }
                    if (p.getX() >= 675){
                        p.move(675, p.getY());
                    }
                    if (p.getX() <= -12){
                        p.move(-12, p.getY());
                    }
                    RepaintAllEnemys();
                    Enemy.UpdateAll();
                    playerImage.repaint();
                    RepaintPlayer();
                    enemys.Update();
                    b.Update();
                    f.repaint();
                    if (info != true){
                        f.repaint();
                    }
                    if (last == 10){
                        Random r = new Random();
                        int x = 1+r.nextInt(2), y = 1+r.nextInt(2), distance = 1+r.nextInt(570), nx = 0, ny = 0;
                        if (x == 1){

                        }
                        last = 0;
                    }
                    last++;
                    u++;
                }
                try {
                    Thread.sleep(10);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }).start();
}

public static void RefreshInfo(){
    f.remove(iy);
    f.remove(ix);
    f.remove(im);
    f.remove(in);
    f.remove(iu);
    f.add(ix);
    f.add(iy);
    f.add(im);
    f.add(in);
    f.add(iu);
    iy.setLocation(0, 10);
    ix.setLocation(0, 20);
    im.setLocation(0, 30);
    in.setLocation(0, 40);
    iu.setLocation(0, 50);
    iu.setBounds((int) iu.getLocation().getX(), (int) iu.getLocation().getY(), 200, 15);
    iy.setBounds((int) iy.getLocation().getX(), (int) iy.getLocation().getY(), 100, 15);
    ix.setBounds((int) ix.getLocation().getX(), (int) ix.getLocation().getY(), 100, 15);
    im.setBounds((int) im.getLocation().getX(), (int) im.getLocation().getY(), 100, 15);
    in.setBounds((int) in.getLocation().getX(), (int) in.getLocation().getY(), 100, 15);
    f.repaint();
}

public static void UpdateAll(){

}

public static void Paint(JLabel imgs, int x, int y, Icon file){
    Icon img = file;
    imgs.setIcon(img);
    imgs.setBounds(x, y, img.getIconWidth(), img.getIconHeight());
    imgs.setLocation(x, y);
    imgs.setVisible(true);
    f.add(imgs);
    imgs.setVisible(true);
}

public static void addBullet(JLabel l, int x, int y, Icon icon){
    Paint(l, x, y, icon);
    bullets.add(l);
}

public static void moveBullet(int newX, int newY, JLabel label){
    if (bullets.contains(label)){
        label.setLocation(newX, newY);
        label.repaint();
        f.repaint();
        label.setVisible(true);
    }
}

public static void Repaint(JLabel l){
    f.remove(l);
    l.setBounds((int)l.getLocation().getX(), (int)l.getLocation().getY(), l.getWidth(), l.getHeight());
    f.add(l);
}

public static void addAE(JLabel l){
    ae.add(l);
}

public static void RepaintAllEnemys(){
    for (int i = 0; i < ae.size(); i++){
        ae.get(i).repaint();
    }
}

public static void MovePlayer(int x, int y){
    playerImage.setLocation(x, y);
    playerImage.repaint();
    f.repaint();
}

public static void paint(JLabel l, int Y, int X){
    l.setLocation(X, Y);
    l.setBounds(X, Y, l.getIcon().getIconWidth(), l.getIcon().getIconHeight());
    l.setVisible(true);
    f.add(l);
    l.setVisible(true);
    l.repaint();
    f.repaint();
}

public static void RepaintPlayer(){
    if (p.isAttacking() == true){
        if (pt == Playere.Kaneki){
            if (attacking == false){
                ImageIcon img = new ImageIcon(StartMenu.class.getResource("/Schoo/NewGame/Kaneki_hit.png"));
                playerImage.setIcon(img);
                playerIcon = img;
                attacking = true;
                imageIcon = img;
            }
        }
        if (pt == Playere.Touka){
            if (attacking == false){
                ImageIcon img = new ImageIcon(StartMenu.class.getResource("/Schoo/NewGame/touka_shoot.png"));
                playerImage.setIcon(img);
                playerIcon = img;
                attacking = true;
                imageIcon = img;
            }
        }
    }else{
        if (pt == Playere.Kaneki){
            if (attacking == true){
                ImageIcon img = new ImageIcon(StartMenu.class.getResource("/Schoo/NewGame/Kaneki_walk.png"));
                playerImage.setIcon(img);
                playerIcon = img;
                attacking = false;
                imageIcon = img;
            }
        }
        if (pt == Playere.Touka){
            if (attacking == true){
                ImageIcon img = new ImageIcon(StartMenu.class.getResource("/Schoo/NewGame/touka_walk.png"));
                playerImage.setIcon(img);
                playerIcon = img;
                attacking = false;
                imageIcon = img;
            }
        }
    }
    turnPlayer(p.getDirection());
    MovePlayer(p.getX(), p.getY());
    playerImage.repaint();
    f.repaint();
}

public static void paintplayer(){
    if (pt == Playere.Kaneki){
        ImageIcon imgs = new ImageIcon(StartMenu.class.getResource("/schoo/NewGame/kaneki_walk.png"));
        playerImage.setIcon(imgs);
        playerImage.setBounds(p.getX(), p.getY(), imgs.getIconWidth(), imgs.getIconHeight());
        playerImage.setLocation(274, 277);
        playerImage.setVisible(true);
        f.add(playerImage);
        playerImage.setVisible(true);
        imageIcon = imgs;
    }
    if (pt == Playere.Touka){
        playerImage.setIcon(new ImageIcon(StartMenu.class.getResource("/schoo/NewGame/touka_walk.png")));
        playerImage.setBounds(p.getX(), p.getY(), new ImageIcon(StartMenu.class.getResource("/schoo/NewGame/touka_walk.png")).getIconWidth(), new ImageIcon(StartMenu.class.getResource("/schoo/NewGame/touka_walk.png")).getIconHeight());
        playerImage.setLocation(274, 277);
        playerImage.setVisible(true);
        f.add(playerImage);
        playerImage.setVisible(true);
        playerIcon = playerImage.getIcon();
    }
}

public static Bullets getBullets(){
    return b;
}
Icon icon;
public void turn(Direction d){
    if (pt == Playere.Kaneki){
        icon = new SafeIcon(playerImage.getIcon());
        BufferedImage bi = new BufferedImage(icon.getIconWidth(), icon.getIconHeight(), BufferedImage.TYPE_INT_RGB);
        Graphics2D g = (Graphics2D) bi.getGraphics();
        if (d == Direction.LEFT && p.getDirection() == Direction.UP){
            g.rotate(Math.PI / 2, playerImage.getWidth(), playerImage.getHeight());
            playerImage.getIcon().paintIcon(null, g, 0, 0);
            g.dispose();
        }
    }
    if (pt == Playere.Touka){

    }
}

public static void turnPlayer(Direction d){
    try {
        TheRealGame.class.newInstance().turn(d);
    } catch (InstantiationException e) {
        System.out.println("Something went wrong!");
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        System.out.println("Something went wrong!");
        e.printStackTrace();
    }
}

public enum Direction{
    LEFT, UP, RIGHT, DOWN;
}
}

1 个答案:

答案 0 :(得分：0)

那是因为当您在SafeIcon中创建icon = new SafeIcon(playerImage.getIcon());实例时，您正在为wrapee变量定义null。

如果你需要wrapee为非null值，请调整构造函数以使其更安全，这样可以更容易地检测NPE的根本原因：

public SafeIcon(Icon icon) {
    if (icon == null) {
        throw new NullPointerException("icon"); // or IllegalArgumentException
    }
    this.wrapee = icon;
}

然后检查playerImage JLabel实例是否应始终定义图标。如果是这样，请为其定义一个图标，您的问题就会得到解决。

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