未触发onFling事件

Question

我正在测试向左和向右滑动我的活动。我有以下代码：

public class MainActivity extends AppCompatActivity implements LocationListener, GestureDetector.OnGestureListener {
   ...
   private GestureDetectorCompat gestureDetector;
   ...
   protected void onCreate(Bundle savedInstanceState) {
     ...
     gestureDetector = new GestureDetectorCompat(this, this);
     ...
   }

   public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {

        if (Math.abs(e1.getY() - e2.getY()) > SWIPE_MAX_OFF_PATH)
            return false;


        if (e1.getX() - e2.getX() > SWIPE_MIN_DISTANCE
                && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
            // right to left swipe
            Toast.makeText(getApplicationContext(), "right to left swipe", Toast.LENGTH_LONG);

        } else if (e2.getX() - e1.getX() > SWIPE_MIN_DISTANCE
                && Math.abs(velocityX) > SWIPE_THRESHOLD_VELOCITY) {
            Toast.makeText(getApplicationContext(), "left to right swipe", Toast.LENGTH_LONG);
        }

    Log.i("EVENT:", "Event triggered");
    return true;
  }


  public boolean onTouchEvent(MotionEvent event) {
    gestureDetector.onTouchEvent(event);

    return super.onTouchEvent(event);
  }

我希望当我向左和向右滑动时会调用onFling方法。但我在onFling中的任何消息都不会被调用。当我查看控制台时，我只看到以下内容：

I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_DOWN
I/ViewRootImpl: ViewRoot's Touch Event : ACTION_UP

我可能做错了什么？

Answer 1

当此问题发生在您身上时，很可能是由于布局中的某个元素造成的。我有一个RelativeLayout的子元素，它匹配父元素的高度和宽度：

<ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_centerHorizontal="true" android:id="@+id/listView" android:layout_alignParentTop="true"/>

当我删除它时，onFling事件被调用。