Android Andengine LiveWallpaper中的空指针异常

我正在使用AnEngine Live墙纸扩展制作LiveWallper。问题是，当我试图在onCreateSecene方法中附加一个精灵（背景图像）时，我得到一个空指针异常。有人能帮我吗

以下是我的密码：

@Override
public EngineOptions onCreateEngineOptions() {

    this.mCamera = new Camera(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT);
    EngineOptions engineOptions = new EngineOptions(false, ScreenOrientation.PORTRAIT_FIXED, new RatioResolutionPolicy(CAMERA_WIDTH, CAMERA_HEIGHT), mCamera);
    return engineOptions;

}

@Override
public void onCreateResources(
        OnCreateResourcesCallback rsrCallback)
        throws Exception {

    BitmapTextureAtlasTextureRegionFactory.setAssetBasePath("gfx/"); 
    background = new BitmapTextureAtlas(this.getTextureManager(), 480, 320);
    backTR = BitmapTextureAtlasTextureRegionFactory.createFromAsset(background,this.getAssets(), "background_small.png", 0, 0);
    background.load();

    rsrCallback.onCreateResourcesFinished();
}

@Override
public void onCreateScene(OnCreateSceneCallback sceneCallback)
        throws Exception {
    // creating main scene
    mMainScene = new Scene();
    IBackground myBack = new  Background(0.0f, 0.0f, 0.0f);
    mMainScene.setBackground(myBack);

    final Sprite bkground = new Sprite(0, 0, CAMERA_WIDTH, CAMERA_HEIGHT, backTR, getVertexBufferObjectManager());
    mMainScene.getLastChild().attachChild(bkground);

    sceneCallback.onCreateSceneFinished(mMainScene);  
}

在mMainScene.getLastChild（）attachChild（bkground）行上，我得到一个空指针。堆栈跟踪已附加

---

我找到了另一种解决方案，在墙纸上添加精灵背景

使用SpriteBackground类：-

mMainScene.setBackground(new SpriteBackground(new Sprite(0, 0, backTR, this.getVertexBufferObjectManager())));

---

这解决了我之前得到的空指针。

+1用于自己解决此问题。关键是在onPopulateScene中附加精灵，因为在调用OnCreateCallback之前，其他AndEngine方法无法使用mMainScene。