Android How to detect double tap?

Question

I'm trying to refresh Canvas on DoubleTap in android. I use GestureDetector in custom View.

final GestureDetector mDetector = new GestureDetector(
    getContext(), new GestureDetector.OnGestureListener() {

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

But I'm getting the error

The method onDoubleTap(MotionEvent) of type new GestureDetector.OnGestureListener(){} must override or implement a supertype method

with

Remove '@Override' annotation

solution. I remove override and get this warning

The method onDoubleTap(MotionEvent) from the type new GestureDetector.OnGestureListener() {} is never used locally.

Then I tried to test whether this works and made a function to change TextView string whenever I DoubleTap. Nothing happens.

I also looked at GestureDetector Reference for explanations, but they don't even have DoubleTap there, which everybody uses. What should I do?

I think the following link will help you http://stackoverflow.com/questions/2640119/how-to-detect-doubletap-on-a-view — Prasad, Aug 16 '15 at 18:03

score 2 · Accepted Answer · answered Aug 16 '15 at 18:08

2

try this

final GestureDetector mDetector = new GestureDetector(getContext(), new GestureDetector.SimpleOnGestureListener {

    @Override
    public boolean onDown(MotionEvent e) {

        return true;
    }

    @Override
    public boolean onDoubleTap(MotionEvent e) {

        return true;
    }
});

answered Aug 16 '15 at 18:08

Davide

126
8

Nope it does not work. `The value of the local variable Detector is not used` - highlighted mDetector warning. – Oleksandr Firsov Aug 16 '15 at 19:02
I check whether stuff works by writing this function - `text = MainActivity.text` `text.setText("stuff")` – Oleksandr Firsov Aug 16 '15 at 19:03
With some other sources I made it work, but now I have a problem - I use this in `WebView`, so double tap zooms in and out, and I have `GestureDetector.OnGestureListener`. When I use also `SimpleOnGestureListener` zooming is disabled. – Oleksandr Firsov Aug 17 '15 at 14:00
please note that the warning "The value of the local variable Detector is not used" is not an error, so you need to set the detector `mDetector.setOnDoubleTapListener(this);`. Try to read this is vr useful https://developer.android.com/training/gestures/detector.html – Davide Aug 17 '15 at 14:04
Yep. This link did the thing, but again, now zooming feature's disabled. How can I keep both of them? – Oleksandr Firsov Aug 17 '15 at 14:59
i suggest to close this question and open another one where you'll able to post more detailed code for this issue (in this way more people can help you) – Davide Aug 17 '15 at 15:08

score 1 · Answer 2 · answered Feb 05 '21 at 10:58

For the ones, who were wondering how to set it also to the corresponding view:

final GestureDetector gDetector = new GestureDetector(getBaseContext(), new GestureDetector.SimpleOnGestureListener() {

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

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

// Set it to the view
mButton.setOnTouchListener((v, event) -> gDetector.onTouchEvent(event));

score 0 · Answer 3 · answered Feb 20 '21 at 19:09

My approach to this problem was different since I needed to perform something for the onClick listener as well, and also it was in a list view, so I needed to know what was the item content. here is my approach using kotlin Job: At the top of the class I've declared something like this:

private var doubleTapTimerJob: Job = Job()
private var clickedViewItem: CartViewItem? = null
val DOUBLE_TAP_DELAY = 200L

where CartViewItem is the model that is used in the list. and this is my onClickListener logic:

if (clickedViewItem == null || clickedViewItem != cartViewItem) {
    doubleTapTimerJob.cancel()
    doubleTapTimerJob = lifecycleScope.launch {
        delay(DOUBLE_TAP_DELAY)
        clickedViewItem = null
    }
    clickedViewItem = cartViewItem
    onClicked(cartViewItem)
} else {
    onDoubleClicked(cartViewItem)
    clickedViewItem = null
    doubleTapTimerJob.cancel()
}

here I wait for 200 milliseconds for the second tap, and if it didn't happen, I will make clickedViewItem null, so its not valid anymore

Android How to detect double tap?

3 Answers3

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