Question

我正在使用Cocos2D在Android中制作2D游戏，用Java编写。这是我的主要代码：

public void gameLoop(float dt) {
    //Player Gravity
    if(canExecuteMovement(0, 6)) {
        guy.moveY(6);
    }

    //Player Movement
    if(direction == 1) {
        if(canExecuteMovement(-3, 0))
            guy.moveX(-3);
    } else if(direction == 2) {
        if(canExecuteMovement(3, 0))
            guy.moveX(3);
    }
}

private boolean canExecuteMovement(int xChange, int yChange) {
    int projectedX = guy.getBounds().left + xChange;
    int projectedY = guy.getBounds().top + yChange;
    Log.i("DD", "guy:" + guy.getBounds().toString());
    Rect projectedBounds = new Rect(projectedX, projectedY, projectedX + guy.getWidth(), projectedY + guy.getHeight());
    Log.i("DD", "guy:" + projectedBounds.toString());
    for (int i = 0; i < platformCount; i++) {
        if (Rect.intersects(projectedBounds, platform[i].getBounds())) {
            return false;
        }
    }

    return true;
}

如你所见，这个函数看起来很好，canExecuteMovement中的矩形也很好，但是在这一行中：

LINE 107: if (Rect.intersects(projectedBounds, platform[i].getBounds())) {

我收到一个InvocationTargetException。这是logcat：

01-21 23:10:12.601: W/System.err(13118): java.lang.reflect.InvocationTargetException
01-21 23:10:12.601: W/System.err(13118):    at java.lang.reflect.Method.invokeNative(Native Method)
01-21 23:10:12.605: W/System.err(13118):    at java.lang.reflect.Method.invoke(Method.java:511)
01-21 23:10:12.605: W/System.err(13118):    at org.cocos2d.actions.CCTimer.update(CCTimer.java:82)
01-21 23:10:12.605: W/System.err(13118):    at org.cocos2d.actions.CCScheduler.tick(CCScheduler.java:253)
01-21 23:10:12.605: W/System.err(13118):    at org.cocos2d.nodes.CCDirector.drawCCScene(CCDirector.java:679)
01-21 23:10:12.605: W/System.err(13118):    at org.cocos2d.nodes.CCDirector.onDrawFrame(CCDirector.java:649)
01-21 23:10:12.605: W/System.err(13118):    at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1462)
01-21 23:10:12.605: W/System.err(13118):    at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1216)
01-21 23:10:12.605: W/System.err(13118): Caused by: java.lang.NullPointerException
01-21 23:10:12.608: W/System.err(13118):    at com.qasim.platformer.GameLayer.canExecuteMovement(GameLayer.java:107)
01-21 23:10:12.608: W/System.err(13118):    at com.qasim.platformer.GameLayer.gameLoop(GameLayer.java:86)
01-21 23:10:12.608: W/System.err(13118):    ... 8 more
01-21 23:10:12.620: D/dalvikvm(13118): GC_CONCURRENT freed 460K, 6% free 9279K/9863K, paused 2ms+3ms
01-21 23:10:12.624: I/DD(13118): guy:Rect(252, 63 - 300, 111)

可能是什么问题？ man中的getBounds（）类是这样的：

public Rect getBounds() {
    return new Rect(x, y, x+width, y+height);
}

Answer 1

InvocationTargetException只是动态调用中抛出的异常的包装器。真正的问题是它正在包装的NullPointerException：

Caused by: java.lang.NullPointerException
  at com.qasim.platformer.GameLayer.canExecuteMovement(GameLayer.java:107)
  at com.qasim.platformer.GameLayer.gameLoop(GameLayer.java:86)

正如您所指出的，这是违规行：

if (Rect.intersects(projectedBounds, platform[i].getBounds())) {

此行上唯一可能发生空指针的地方是platform[i].getBounds()。 platform本身为null，或platform[i]的元素为。{/ p>

为什么我收到InvocationTargetException？ Android 2D游戏

1 个答案: