Question

我一直在通过youtube教程开发一款游戏，你们中的一些人可能认为它是由设计者提供的，并且遇到了一个问题。我很确定代码是正确的，因为我在之前的项目中使用过之前的调用。即使使用github上发布的完整项目源代码，我也会得到一个数组超出范围的异常。有什么建议？

    package Game;

import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import java.awt.image.BufferedImage;
import java.awt.image.DataBufferInt;

import javax.swing.JFrame;

import GFX.Screen;
import GFX.SpriteSheet;

public class Game extends Canvas implements Runnable {
private static final long serialVersionUID = 1L;

public static final int WIDTH = 160;
public static final int HEIGHT = WIDTH / 12 * 9;
public static final int SCALE = 3;

public static final String NAME = "Game";

private JFrame frame;

public boolean running = false;
public int tickcount = 0;

private BufferedImage image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
private int[] pixels = ((DataBufferInt) image.getRaster().getDataBuffer()).getData();

private Screen screen;

public Game() {
    setMinimumSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
    setMaximumSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));
    setPreferredSize(new Dimension(WIDTH * SCALE, HEIGHT * SCALE));

    frame = new JFrame(NAME);

    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLayout(new BorderLayout());

    frame.add(this, BorderLayout.CENTER);
    frame.pack();

    frame.setResizable(false);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}

public void init() {
    screen = new Screen(WIDTH, HEIGHT, new SpriteSheet("/Sprites/spritesheet.png"));
}

public void render() {
    BufferStrategy bs = getBufferStrategy();
    if (bs == null) {
        createBufferStrategy(3);
        return;
    }
    screen.render(pixels, 0, WIDTH);

    Graphics g = bs.getDrawGraphics();
    g.drawImage(image, 0, 0, getWidth(), getHeight(), null);

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

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

public synchronized void stop() {
    running = false;
}

public void run() {
    long lastTime = System.nanoTime();
    double nsPerTick = 1000000000D / 60D;

    int ticks = 0;
    int frames = 0;

    long lastTimer = System.currentTimeMillis();
    double delta = 0;

    init();

    while (running) {
        long now = System.nanoTime();
        delta += (now - lastTime) / nsPerTick;
        lastTime = now;
        boolean shouldRender = true;

        while (delta >= 1) {
            ticks++;
            tick();
            delta -= 1;
            shouldRender = true;
        }

        try {
            Thread.sleep(2);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        if (shouldRender) {
            frames++;
            render();
        }

        if (System.currentTimeMillis() - lastTimer >= 1000) {
            lastTimer += 1000;
            frames = 0;
            ticks = 0;
        }
    }
}

public void tick() {
    tickcount++;

    for (int i = 0; i < pixels.length; i++)
        pixels[i] = i + tickcount;
}

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

}

    package GFX;

    import java.awt.image.BufferedImage;
    import java.io.IOException;

    import javax.imageio.ImageIO;


    public class SpriteSheet {

public String path;
public int width;
public int height;

public int[] pixels;

public SpriteSheet(String path) {
    BufferedImage image = null;

    try 
    {
        image = ImageIO.read(SpriteSheet.class.getResourceAsStream(path));
    }
    catch (IOException e) 
    {
        e.printStackTrace();
    }

    if (image == null) return;

    this.path = path;
    this.width = image.getWidth();
    this.height = image.getHeight();

    pixels = image.getRGB(0, 0, width, height, null, 0, width);

    for (int i = 0; i < pixels.length; i++) {
        pixels[i] = (pixels[i] & 0xff) / 64;
    }
    for (int i = 0; i < 8; i++)
        System.out.println(pixels[i]);
}

}

    package GFX;

    public class Screen {
public static final int MAP_WIDTH = 64;
public static final int MAP_WIDTH_MASK = MAP_WIDTH - 1;

public int[] tiles = new int[MAP_WIDTH * MAP_WIDTH];
public int[] colors = new int[MAP_WIDTH * MAP_WIDTH];

public int xOffset = 0;
public int yOffset = 0;

public int width;
public int height;

public SpriteSheet sheet;

public Screen(int width, int height, SpriteSheet sheet) {
    this.width = width;
    this.height = height;
    this.sheet = sheet;

    for (int i = 0; i < MAP_WIDTH * MAP_WIDTH; i++) {
        colors[i * 4 + 0] = 0xff00ff;
        colors[i * 4 + 1] = 0x00ffff;
        colors[i * 4 + 2] = 0xffff00;
        colors[i * 4 + 3] = 0x0000ff;
    }
}

public void render(int[] pixels, int offset, int row) {
    for (int yTile = yOffset >> 3; yTile <= (yOffset + height) >> 3; yTile++) {
        int yMin = yTile * 8 - yOffset;
        int yMax = yMin + 8;
        if (yMin < 0)
            yMin = 0;
        if (yMin > height)
            yMax = height;

        for (int xTile = xOffset >> 3; xTile <= (xOffset + width) >> 3; xTile++) {
            int xMin = xTile * 8 - xOffset;
            int xMax = xMin + 8;
            if (xMin < 0)
                xMin = 0;
            if (xMin > width)
                xMax = width;

            int tileIndex = (xTile & (MAP_WIDTH_MASK))
                    + (yTile & (MAP_WIDTH_MASK)) * MAP_WIDTH;

            for (int y = yMin; y < yMax; y++) {
                int sheetPixel = ((y + yOffset) & 7) * sheet.width
                        + ((xMin + xOffset) & 7);
                int tilePixel = offset + xMin + y * row;

                for (int x = xMin; x < xMax; x++) {
                    int color = tileIndex * 4 + sheet.pixels[sheetPixel++];
                    pixels[tilePixel++] = colors[color];
                }
            }
        }
    }
}

}

到目前为止，这是所有代码。错误如下线程“Thread-2”中的异常java.lang.IllegalArgumentException：input == null！在javax.imageio.ImageIO.read（未知来源）在GFX.SpriteSheet。（SpriteSheet.java:22）在Game.Game.init（Game.java:54）在Game.Game.run（Game.java:91）在java.lang.Thread.run（未知来源）

Answer 1

就在这一行

image = ImageIO.read(SpriteSheet.class.getResourceAsStream(path));

你的程序找不到文件所以它返回null并且当你尝试从null读取时会抛出空指针异常

你需要确保相对于你运行程序的位置有一个“/Sprites/spritesheet.png”文件

数组越界错误

1 个答案: