android - 从未调用 MotionEvent.ACTION_UP

Question

I want to do some works while the user hold his hand on a view and stop it when he release it. My code is below:

viewHolder.plus.setOnTouchListener(new View.OnTouchListener() {
        private Handler mHandler;
        @Override
        public boolean onTouch(View view, MotionEvent event) {
            switch(event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    if(mHandler==null)
                        mHandler = new Handler();
                    mHandler.postDelayed(mAction, 500);
                    return true;
                case MotionEvent.ACTION_UP:
                    Log.v("this","cancel");
                    if (mHandler != null) {
                        mHandler.removeCallbacks(mAction);
                        mHandler = null;
                        Log.v("this", "c cancel");
                    }
                    break;
            }
            return false;
        }

        Runnable mAction = new Runnable() {
            @Override public void run() {
                ChangeTedad(item.getid(), "plus");
                Log.v("this","Cc");
                mHandler.postDelayed(this, 500);
            }
        };

    });

the problem is, ACTION_UP is never called and the runnable stays run forever.

How to stop the runnable when the user un touch it?

Answer 1

You have not properly set break and return flag in touch event.

Please replace your code with,

viewHolder.plus.setOnTouchListener(new View.OnTouchListener() {
        private Handler mHandler;
        @Override
        public boolean onTouch(View view, MotionEvent event) {
            switch(event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    if(mHandler==null)
                        mHandler = new Handler();
                    mHandler.postDelayed(mAction, 500);
                    break;
                case MotionEvent.ACTION_UP:
                    Log.v("this","cancel");
                    if (mHandler != null) {
                        mHandler.removeCallbacks(mAction);
                        mHandler = null;
                        Log.v("this", "c cancel");
                    }
                    break;
            }
            return true;
        }

        Runnable mAction = new Runnable() {
            @Override public void run() {
                ChangeTedad(item.getid(), "plus");
                Log.v("this","Cc");
                mHandler.postDelayed(this, 500);
            }
        };
    });

Hope this will help you

Answer 2

Whenever you do a single touch in a view, Android will create a series of touch events instead of a single touch event and buffer these events then call onTouch method sequentially based on returned value from that method.

For example when you do a single touch on a view, the normal sequence of events will be

• ACTION_DOWN (when you put your finger down)
• optionally ACTION_MOVE (if you move your finger while touching the screen)
• ACTION_UP (when you remove your finger from the screen)

However, if you return false from the onTouchEvent override in response to an ACTION_XXX event, you will not be notified (your code will not be executed) about any subsequent events.

Back to your case, because you return false from onTouchEvent , so after receiving first event ( ACTION_DOWN ), all subsequent events (including ACTION_UP ) will not be called.

All you need to do is return true from onTouchEvent method. That's it!

viewHolder.plus.setOnTouchListener(new View.OnTouchListener() {
    private Handler mHandler;

    @Override
    public boolean onTouch(View view, MotionEvent event) {
        switch(event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                if (mHandler == null) {
                    mHandler = new Handler();
                }
                mHandler.postDelayed(mAction, 500);
                break;
            case MotionEvent.ACTION_UP:
                Log.v("this","cancel");
                if (mHandler != null) {
                    mHandler.removeCallbacks(mAction);
                    mHandler = null;
                    Log.v("this", "c cancel");
                }
                break;
        }

        // [IMPORTANT] Return true here
        return true;
    }

    Runnable mAction = new Runnable() {
        @Override public void run() {
            ChangeTedad(item.getid(), "plus");
            Log.v("this","Cc");
            mHandler.postDelayed(this, 500);
        }
    };
}); 

This is a really good post that explains about touch handing in Android. Take a look at it when you have time.

Answer 3

You can also add your ACTION_UP logic codes to ACTION_CANCEL , cause of, if you touch the view and release it, it will call to ACTION_UP , but if you are at view pressed state and you move even 1 Pixel, it will NOT call ACTION_UP , and call only ACTION_CANCEL . Hope this will help for you.

viewHolder.plus.setOnTouchListener(new View.OnTouchListener() {
        private Handler mHandler;
        @Override
        public boolean onTouch(View view, MotionEvent event) {
            switch(event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    if(mHandler==null)
                        mHandler = new Handler();
                    mHandler.postDelayed(mAction, 500);
                    return true;
                case MotionEvent.ACTION_UP:
                    Log.v("this","cancel");
                    if (mHandler != null) {
                        mHandler.removeCallbacks(mAction);
                        mHandler = null;
                        Log.v("this", "c cancel");
                    }
                    break;
                case MotionEvent.ACTION_CANCEL:
                    Log.v("this","cancel");
                    if (mHandler != null) {
                        mHandler.removeCallbacks(mAction);
                        mHandler = null;
                        Log.v("this", "c cancel");
                    }
                    break;
            }
            return false;
        }

        Runnable mAction = new Runnable() {
            @Override public void run() {
                ChangeTedad(item.getid(), "plus");
                Log.v("this","Cc");
                mHandler.postDelayed(this, 500);
            }
        };

    });