加速度計+ Touchで車を移動するタッチ

Question

タッチイベントと加速度計を組み合わせてSurfaceViewにオブジェクトを移動するのに問題があります。

私は次の行にNullPointerExceptionがを取得しています：

player = new Player((SensorManager)mContext.getSystemService (Context.SENSOR_SERVICE), BitmapFactory.decodeResource(getResources(), R.drawable.helicopter), 65, 25, 3); 

そして、これは私にが並んで "itselfeに割り当てられている" ヒント与えない：

this.mContext = mContext; 

をどのI推測は問題の原因になる可能性がありますが、私は自分の問題をどのように処理するかを知りません。

これは、SurfaceViewから拡張されたクラスです。

public class GamePanel extends SurfaceView implements SurfaceHolder.Callback{ 
private MainThread thread; 
private Background bg; 
public static final int MOVESPEED = -5; 
public static final int WIDTH = 856; 
public static final int HEIGTH = 480; 
private Player player; 
Context mContext; 

public GamePanel(Context context){ 
    super(context); 
    getHolder().addCallback(this); 
    this.mContext = mContext; 
    thread = new MainThread(getHolder(), this); 
    setFocusable(true); //damit kann das ding Events handeln! WOW!! 
} 
@Override 
public void surfaceCreated(SurfaceHolder holder) { 
    bg = new Background(BitmapFactory.decodeResource(getResources(), R.drawable.grassbg1)); 
    player = new Player((SensorManager)mContext.getSystemService(Context.SENSOR_SERVICE),BitmapFactory.decodeResource(getResources(), R.drawable.helicopter), 65, 25, 3); 
    thread.setRunning(true); 
    thread.start(); 
} 
@Override 
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { 
} 
@Override 
public void surfaceDestroyed(SurfaceHolder holder) { 
    boolean retry = true; 
    while(retry){ 
     try{thread.setRunning(false); 
      thread.join(); 
     }catch(InterruptedException e){e.printStackTrace();} 
     retry = false; 
    } 
} 
@Override 
public boolean onTouchEvent (MotionEvent event){ 
    if(event.getAction()==MotionEvent.ACTION_DOWN){ 
     if(!player.getPlaying()){ 
      player.setPlaying(true); 
     } 
     else{ 
      player.setUp(true); 
     } 
     return true; 
    } 
    if(event.getAction()==MotionEvent.ACTION_UP){ 
     player.setUp(false); 
     return true; 
    } 
    return super.onTouchEvent(event); 
} 
public void update(){ 
    if(player.getPlaying()) { 
     bg.update(); 
     player.update(); 
    } 
} 
@Override 
public void draw(Canvas canvas){ 
    final float scaleFactorX = getWidth()/(WIDTH*1.f); 
    final float scaleFactorY = getHeight()/(HEIGTH*1.f); 
    if(canvas != null){ 
     final int savedState = canvas.save(); 
     canvas.scale(scaleFactorX, scaleFactorY); 
     bg.draw(canvas); 
     player.draw(canvas); 
     canvas.restoreToCount(savedState); 
    } 
} 

これは、移動または単純な物理を行う「プレーヤー」クラスです。

public class Player extends GameObject implements SensorEventListener{ 
private Bitmap spritesheet; 
private int score; 
private float accX, accY; 
private double dya; 
private boolean up; 
private boolean playing; 
private Animation animation = new Animation(); 
private long startTime; 
private SensorManager sensorManager; 

public Player(SensorManager sensorManager, Bitmap res, int w, int h, int numFrames){ 
    x = 100; 
    y = GamePanel.HEIGTH/2; 
    dy = 0; 
    score = 0; 
    height = h; 
    width = w; 

    Bitmap[] image = new Bitmap[numFrames]; 
    spritesheet = res; 

    for(int i = 0; i < image.length; i++){ 
     image[i] = Bitmap.createBitmap(spritesheet, i*width, 0, width, height); 
    } 
    animation.setFrames(image); 
    animation.setDelay(10); 
    startTime = System.nanoTime(); 
} 
@Override 
public void onSensorChanged(SensorEvent sensorEvent) { 
    accX = (sensorEvent.values[1]); 
    accY = (sensorEvent.values[2]); 
} 
@Override 
public void onAccuracyChanged(Sensor sensor, int i){ 
    //not needed 
} 

public void setUp(boolean b){up = b;} 

public void update(){ 
    Sensor sensor = sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER); 
    sensorManager.registerListener(this, sensor, SensorManager.SENSOR_DELAY_NORMAL); 

    animation.update(); 
    if(up){ 
     dy = (int)(dya-=1.1); 
    } 
    else{ 
     dy = (int)(dya+=1.1); 
    } 
    if(dy>14)dy = 14; 
    if(dy<-14)dy = -14; // dies begrenzd die maximale geschwindigkeit 

    y += dy+(10*accY); 
    dy = 0; 
} 
public void draw(Canvas canvas){ 
    canvas.drawBitmap(animation.getImage(),x,y,null); 
} 
public int getScore(){return score;} 
public boolean getPlaying(){return playing;} 
public void setPlaying(boolean b){playing = b;} 
public void resetDYA(){dya = 0;} 
public void resetScore(){score = 0;} 

Answer 1

あなたの問題は、多分あなたはthis.mContext = mContext;を使用しますが、私はあなたがthis.mContext = context;