手势向右或向左滑动不起作用

Question

我想从按钮更改为滑动，以便获取我的Android应用程序中的下一个和上一个元素。我已经看过Gestures的一些实现，主要是在stackoverflow中，但是在编写类似的代码后，它似乎不起作用。我想知道为什么我会想念。我只想实现向右滑动和向左滑动以获取下一个和上一个元素。这是应用程序中有关此问题的相关部分。谢谢

public class MainActivity extends AppCompatActivity {

    public GestureDetector gestureDetector;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void OnSwipeTouchListener (Context ctx){
        gestureDetector = new GestureDetector(ctx, new GestureListener());
    }

    public boolean onTouch(View v, MotionEvent event) {
        return gestureDetector.onTouchEvent(event);
    }

    private final class GestureListener extends GestureDetector.SimpleOnGestureListener {

        private static final int SWIPE_THRESHOLD = 100;
        private static final int SWIPE_VELOCITY_THRESHOLD = 100;

        @Override
        public boolean onDown(MotionEvent e) {
            return true;
        }

        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
            boolean result = false;
            try {
                float diffY = e2.getY() - e1.getY();
                float diffX = e2.getX() - e1.getX();
                if (Math.abs(diffX) > Math.abs(diffY)) {
                    if (Math.abs(diffX) > SWIPE_THRESHOLD && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {
                        if (diffX > 0) {
                            onSwipeRight();
                        } else {
                            onSwipeLeft();
                        }
                        result = true;
                    }
                }
                else if (Math.abs(diffY) > SWIPE_THRESHOLD && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {
                    if (diffY > 0) {
                        onSwipeBottom();
                    } else {
                        onSwipeTop();
                    }
                    result = true;
                }
            } catch (Exception exception) {
                exception.printStackTrace();
            }
            return result;
        }
    }

    public void onSwipeRight() {
        Toast.makeText(MainActivity.this, "Swipe Right", Toast.LENGTH_SHORT).show();
    }

    public void onSwipeLeft() {
        Toast.makeText(MainActivity.this, "Swipe Left", Toast.LENGTH_SHORT).show();
    }

    public void onSwipeTop() {
    }

    public void onSwipeBottom() {
    }
}