在窗口管理器中膨胀类时出错

Code

public class FloatingWindow extends Service{
WindowManager wm;
LinearLayout ll;
LayoutInflater li;

@Override
public IBinder onBind(Intent intent) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public void onCreate() {
    // TODO Auto-generated method stub
    super.onCreate();
    View myview;
    li = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
    wm = (WindowManager) getSystemService(WINDOW_SERVICE);
    WindowManager.LayoutParams params = new WindowManager.LayoutParams(
            WindowManager.LayoutParams.TYPE_INPUT_METHOD |
            WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY | WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
            WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL,
            PixelFormat.TRANSLUCENT);
    params = new WindowManager.LayoutParams(
            500, 1000, WindowManager.LayoutParams.TYPE_PHONE,
            WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE,
            PixelFormat.TRANSLUCENT);
    params.gravity = Gravity.CENTER | Gravity.CENTER;
    myview = li.inflate(R.layout.service_floating_window, null); // your layout here
    wm.addView(myview, params);
public class FloatingWindow extends Serv