Question

我无法合并触摸事件和加速度计来移动SurfaceView上的对象。

我在下面的行中收到 NullPointerException ：

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

这确实给了我“分配给itselfe”的提示：

this.mContext = mContext;

我想这可能是问题的根源，但我仍然不知道如何处理我的问题。

这是从SurfaceView扩展的类。

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);
    }
}

这是运动或简单物理学的“玩家”类。

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

你的问题可能就是你的游戏面板＆＃34;您使用this.mContext = mContext;的构造函数，但我认为您应该使用this.mContext = context;

Accelerometer + Touch可在SurfaceView中移动汽车

1 个答案: