Gesture Detector not working

Question

I has the following GestureListener:

public class BookListener extends SimpleOnGestureListener implements
        OnTouchListener {
    private LibraryActivity main;
private Book book;
private GestureDetector gesture;

public BookListener(Book book, LibraryActivity main) {
    this.main = main;
    this.book = book;
    gesture = new GestureDetector(main,this);
}

public boolean onDoubleTap(MotionEvent e) {
    main.showInfo(book);
    return true;
}

public boolean onSingleTapConfirmed(MotionEvent e) {
    main.openBook(book.getUrl());
    return true;
}

public boolean onDown(MotionEvent evt){
    return false;
}

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

I add it to my View by this way:

view.setOnTouchListener(new BookListener(book, main));

But when running, the events are not triggered, I debug it, I see the onDown is called, but onSingleTapConfirmed or onDoubleTap nevers works.

What's wrong?

I has this code with works perfectly:

    private class GestureListener extends SimpleOnGestureListener {
        private boolean newEvent = true;
        @Override
        public boolean onDoubleTap(MotionEvent e) {
            document.rescale();
            refreshImage();
            return true;
        }

        public boolean onDown(MotionEvent evt){
            newEvent = true;
            return false;
        }

        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2,
                float distanceX, float distanceY) {
            if (!document.isScaled() && newEvent) {
                Vector2D v = new Vector2D(e2).minus(new Vector2D(e1));
                if (v.getX() > 60 || v.getX() < -60){
                    if (v.getX() < 0)
                        next();
                    else
                        previous();
                    newEvent = false;
                }
            } else {
                img.notifyScroll(-distanceX, -distanceY);
                img.invalidate();
            }
            return true;
        }

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

Answer 1

onDown() must return true even if you don't want to react to that event, or else it will make the detector discard any following event and hence any gesture.