Java 当我触摸精灵时应用程序崩溃-致命异常：UpdateThread

我正在使用AndEngine创建一个应用程序。我有一个精灵（在这个例子中是羊），我想用手触摸它。我设法用主活动类中的一个方法来实现它。我想更好地组织我的代码，所以我创建了一个Sheep类，它构造了一个有身体的精灵，并对其应用了物理

问题是，在我单击新创建的对象（sheep）后，我的应用程序崩溃。精灵在屏幕上显示，物理正在工作

我将复制一段代码，以便您可以看到我所做的：

我在主活动中创建我的Sheep对象，为触摸事件注册它，并将精灵附加到场景：

public void onPopulateScene(Scene pScene,
        OnPopulateSceneCallback pOnPopulateSceneCallback) throws Exception {

    final Sheep sheep = new Sheep(CAMERA_WIDTH/2+200, CAMERA_HEIGHT/2, sheepTextureRegion, getVertexBufferObjectManager(), physicsWorld);

    this.scene.registerTouchArea(sheep);
    this.scene.attachChild(sheep);

    pOnPopulateSceneCallback.onPopulateSceneFinished();
}

这些方法也在主活动中，用于触摸事件：

@Override
public boolean onAreaTouched(TouchEvent pSceneTouchEvent,
        ITouchArea pTouchArea, float pTouchAreaLocalX,
        float pTouchAreaLocalY) {
    if (pSceneTouchEvent.isActionDown()) {
        final IAreaShape sheep = (IAreaShape) pTouchArea;
        /*
         * If we have a active MouseJoint, we are just moving it around
         * instead of creating a second one.
         */
        if (this.mouseJoint == null) {
            // this.mEngine.vibrate(100);
            this.mouseJoint = this.createMouseJoint(sheep,
                    pTouchAreaLocalX, pTouchAreaLocalY);
        }
        return true;
    }
    return false;
}

@Override
public boolean onSceneTouchEvent(Scene pScene, TouchEvent pSceneTouchEvent) {
    if (this.physicsWorld != null) {
        switch (pSceneTouchEvent.getAction()) {
        case TouchEvent.ACTION_DOWN:
            return true;
        case TouchEvent.ACTION_MOVE:
            if (this.mouseJoint != null) {
                final Vector2 vec = Vector2Pool
                        .obtain(pSceneTouchEvent.getX()
                                / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT,
                                pSceneTouchEvent.getY()
                                        / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT);
                this.mouseJoint.setTarget(vec);
                Vector2Pool.recycle(vec);
            }
            return true;
        case TouchEvent.ACTION_UP:
            if (this.mouseJoint != null) {
                this.physicsWorld.destroyJoint(this.mouseJoint);
                this.mouseJoint = null;
            }
            return true;
        }
        return false;
    }
    return false;
}

// ========================
// METHODS
// ========================

private MouseJoint createMouseJoint(IAreaShape sheep,
        float pTouchAreaLocalX, float pTouchAreaLocalY) {
    final Body body = (Body) sheep.getUserData();
    final MouseJointDef mouseJointDef = new MouseJointDef();

    final Vector2 localPoint = Vector2Pool.obtain(
            (pTouchAreaLocalX - sheep.getWidth() * 0.5f)
                    / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT,
            (pTouchAreaLocalY - sheep.getHeight() * 0.5f)
                    / PhysicsConstants.PIXEL_TO_METER_RATIO_DEFAULT);
    this.surface.setTransform(localPoint, 0);

    mouseJointDef.bodyA = this.surface;
    mouseJointDef.bodyB = body;
    mouseJointDef.dampingRatio = 0.95f;
    mouseJointDef.frequencyHz = 30;
    mouseJointDef.maxForce = (200.0f * body.getMass());
    mouseJointDef.collideConnected = true;

    mouseJointDef.target.set(body.getWorldPoint(localPoint));
    Vector2Pool.recycle(localPoint);

    return (MouseJoint) this.physicsWorld.createJoint(mouseJointDef);
}

这是绵羊课：

    public class Sheep extends Sprite {

    // CONSTANTS
    private static final FixtureDef SHEEP_DEF = PhysicsFactory.createFixtureDef(1.0f, 0.2f, 0.1f);
    private final static int CAMERA_WIDTH = 720;
    private final static int CAMERA_HEIGHT = 480;

    //FIELDS

    public Sheep(float pX, float pY, ITextureRegion pTextureRegion,
            VertexBufferObjectManager pVertexBufferObjectManager, PhysicsWorld pWorld)
    {

        super(pX, pY, pTextureRegion, pVertexBufferObjectManager);

        final Sprite sheep = new Sprite(CAMERA_WIDTH / 2 + 200,
                CAMERA_HEIGHT / 2, this.getTextureRegion(),
                this.getVertexBufferObjectManager());
        float width = sheep.getWidthScaled()/32;
        float height = sheep.getWidthScaled()/32;

        final Vector2[] vertices = {
                new Vector2(-0.41797f * width, -0.44531f * height),
                new Vector2(-0.19922f * width, -0.48828f * height),
                new Vector2(+0.06641f * width, -0.52344f * height),
                new Vector2(+0.39844f * width, -0.34375f * height),
                new Vector2(+0.51172f * width, -0.00391f * height),
                new Vector2(+0.35156f * width, +0.50000f * height),
                new Vector2(-0.28516f * width, +0.50000f * height),
                new Vector2(-0.43750f * width, +0.01172f * height)
        };
        final Body body = PhysicsFactory.createPolygonBody(pWorld, this, vertices, BodyType.DynamicBody, SHEEP_DEF);
        body.setUserData(Sheep.this);
        pWorld.registerPhysicsConnector(new PhysicsConnector(this, body, true, true));

    }

}

我想不出是什么问题，也许你能帮我解决一下。这是我第一次使用AndEngine，所以我错过了一些东西

这是LogCat的副本：

10-02 14:24:13.779: E/AndroidRuntime(1968): FATAL EXCEPTION: UpdateThread
10-02 14:24:13.779: E/AndroidRuntime(1968): java.lang.NullPointerException
10-02 14:24:13.779: E/AndroidRuntime(1968):     at com.nightingale.sheepgameandengine.MainActivity.createMouseJoint(MainActivity.java:256)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at com.nightingale.sheepgameandengine.MainActivity.onAreaTouched(MainActivity.java:199)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.entity.scene.Scene.onAreaTouchEvent(Scene.java:413)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.entity.scene.Scene.onSceneTouchEvent(Scene.java:357)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.engine.Engine.onTouchScene(Engine.java:452)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.engine.Engine.onTouchEvent(Engine.java:438)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.input.touch.controller.BaseTouchController$TouchEventRunnablePoolItem.run(BaseTouchController.java:102)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.util.adt.pool.RunnablePoolUpdateHandler.onHandlePoolItem(RunnablePoolUpdateHandler.java:54)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.util.adt.pool.RunnablePoolUpdateHandler.onHandlePoolItem(RunnablePoolUpdateHandler.java:1)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.util.adt.pool.PoolUpdateHandler.onUpdate(PoolUpdateHandler.java:88)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.input.touch.controller.BaseTouchController.onUpdate(BaseTouchController.java:62)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.engine.Engine.onUpdate(Engine.java:584)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.engine.Engine.onTickUpdate(Engine.java:548)
10-02 14:24:13.779: E/AndroidRuntime(1968):     at org.andengine.engine.Engine$UpdateThread.run(Engine.java:820)

---

MainActivity.java:256行必须为空。。显示256行256为：mouseJointDef.maxForce=（200.0f*body.getMass（））；尝试将“return true；”放在OnArearTouch（）方法中（删除return false；语句）。我试过了，没有成功。我也犯了同样的错误