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我想在 SurfaceView 中显示 GPS 速度。

GPS 在 mainActivity-Class 中，因为我在 onCreate 之后需要它。有我的线程类，做循环。还有应该显示所有内容的 GamePanel-Class。

问题是，在 GamePanel 中，我尝试使用 textdraw 显示当前 GPS 速度，但它始终为 0。看起来它并没有真正运行 GPS 方法。这是为什么，有人可以帮忙吗？

public class MainActivity extends Activity implements LocationListener {

float nCurrentSpeed;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

    setContentView(new GamePanel(this));

    LocationManager lm = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
    lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);

    this.onLocationChanged(null);
}

@Override
public void onLocationChanged(Location location) {
    if(location == null){
        nCurrentSpeed = 1;
    }
    else {
        nCurrentSpeed = location.getSpeed();
    }
}

@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
public float getCurrentSpeed() {
    return nCurrentSpeed;
}

}

public class GamePanel extends SurfaceView implements SurfaceHolder.Callback{

private MainThread thread;
private MainActivity mainActivity;

public GamePanel(Context context){
    super(context);
    //add the callback to the surfaceholder to intercept events
    getHolder().addCallback(this);

    thread = new MainThread(getHolder(), this);
    setFocusable(true);
}

@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 void surfaceCreated(SurfaceHolder holder){
    thread.setRunning(true);
    thread.start();

    mainActivity = new MainActivity();
}
public void update(){
}
public void drawText(Canvas canvas){
    Paint paint = new Paint();
    paint.setColor(Color.GREEN);
    paint.setTextSize(100);
    paint.setTypeface(Typeface.create(Typeface.DEFAULT, Typeface.BOLD));

    canvas.drawText("Speed: " + (mainActivity.getCurrentSpeed()), 10, 500, paint);
}

}

我没有显示类 Thread-Class，因为我猜它不相关。让我知道你是否需要看它。

对不起我的英语不好，我来自德国。

我希望能得到你的帮助！！！

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