使用 BufferedImage 加载 Sprite 时出现 JAVA 错误

Question

我正在遵循教程，我遇到了这个错误，我似乎无法弄清楚问题是什么。我想做的就是加载 Sprite 图像。这是代码:

这是错误:

Exception in thread "Thread-0" java.lang.NullPointerException at com.mainpkg.game.Handler.gg(Handler.java:27) at com.mainpkg.game.Game.render(Game.java:107) at com.mainpkg.game.Game.run(Game.java:83) at java.base/java.lang.Thread.run(Thread.java:844)

主要游戏类:

public class Game extends Canvas implements Runnable {

public static final int WIDTH = 800, HEIGHT = WIDTH / 12 * 9;
private Thread thread;
private boolean running = false;
private Handler handler;
private BufferedImage grassTile;

public Game() {
    new Window(WIDTH, HEIGHT, "MOON EXPOLATION", this);
    handler = new Handler(getWidth(), getHeight());
    testImage = loadImage("Resources/GrassTile.png");
}

private BufferedImage loadImage(String path) {
    try {
        BufferedImage loadedImage = ImageIO.read(new FileInputStream(path));
        BufferedImage formattedImage = new BufferedImage(loadedImage.getWidth(), loadedImage.getHeight(),
                BufferedImage.TYPE_INT_RGB);
        formattedImage.getGraphics().drawImage(loadedImage, 0, 0, null);
        return formattedImage;
    } catch (IOException e) {
        e.printStackTrace();
        return null;
    }
}

public synchronized void start() {
    thread = new Thread(this);
    thread.start();
    running = true;
}

public synchronized void stop() {
    try {
        thread.join();
        running = false;
    } catch (Exception e) {
        e.printStackTrace();
    }
}

public void run() {

    int FRAMES = 0;
    int TICKS = 0;
    long lastTime = System.nanoTime();
    double unprocessed = 0;
    double nsPerSecs = 1000000000 / 60.0;
    long Timer = System.currentTimeMillis();
    while (running) {
        long now = System.nanoTime();
        unprocessed += (now - lastTime) / nsPerSecs;
        lastTime = now;

        if (unprocessed >= 1) {
            TICKS++;
            ticks();
            unprocessed -= 1;
        }
        try {
            Thread.sleep(3);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        FRAMES++;
        render();

        if (System.currentTimeMillis() - Timer > 1000) {
            System.out.println("Ticks: " + TICKS + " FPS: " + FRAMES);
            TICKS = 0;
            FRAMES = 0;
            Timer += 1000;
        }
    }
    stop();
}

private void ticks() {

}

void render() {
    BufferStrategy bs = this.getBufferStrategy();
    if (bs == null) {
        super.paint(getGraphics());
        this.createBufferStrategy(3);
        return;
    }
    Graphics g = bs.getDrawGraphics();
    handler.renderImage(testImage, 0, 0);
    handler.render(g);
    // g.setColor(Color.BLACK);
    // g.fillRect(0,0,WIDTH,HEIGHT);

    g.dispose();
    bs.show();
}

public static void main(String[] args) {
    new Game();
}

处理程序类:

public class Handler {

private BufferedImage view;
private int pixels[];

public Handler(int width, int height) {
    view = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

    pixels = ((DataBufferInt) view.getRaster().getDataBuffer()).getData();
}

public void render(Graphics g) {
    g.drawImage(view, 0, 0, view.getWidth(), view.getHeight(), null);
}

public void renderImage(BufferedImage image, int xPosition,int yPosition) {
    int[] imagepixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();

    for(int y = 0; y < image.getHeight(); y++) {
        for(int x = 0; x < image.getWidth(); x++) {
            pixels[(x + xPosition) + (y + yPosition ) * view.getWidth()] =  imagepixels[x +  y * image.getWidth()];
        }
    }
}

Answer 1

问题出在这里:

BufferedImage loadedImage = ImageIO.read(Game.class.getResource(path));

getResource(path) 返回 null，这导致了异常。

尝试将图像路径更改为“Assets/GrassTile.png”

一个提示:

您应该避免使用绝对路径来定位您的资源。这是一个非常糟糕的主意，因为如果您更改项目的位置，它将停止工作，请尝试使用相对路径。