Android button hold to continuously loop a method

Question

I have a button and i set a ontouchlistener to continuously execute a method but as i hold on to the button, it stops executing after 1 method call.

my method basically loops from 2 to 4 continuously.

Below is my code snippet.

broadcastButton = (Button) findViewById(R.id.broadcastButton);
broadcastButton.setText("Loop");
broadcastButton.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                switch (event.getAction()) {
                    case MotionEvent.ACTION_DOWN:
                        broadcastmode = 1;
                        schedulePeriodicMethod();
                        try {
                            Thread.sleep(100);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                        break;
                    case MotionEvent.ACTION_UP:
                        broadcastmode = 0;
                        stopPeriodicMethod();


                }
                return true;
            }
        });

public void schedulePeriodicMethod() {
        exHandler.postDelayed(execution, 100);
    }

    public void stopPeriodicMethod() {
        exHandler.removeCallbacks(execution);
    }

    private Runnable execution = new Runnable() {
        @Override
        public void run() {
            connectDevice(flag);
            serialSend("C");
            flag++;
            if (flag > 4)
                flag = 2;
        }
    };

need help on where am i doing wrong that the program is not looping

user4533681 · Accepted Answer · 2015-02-05 16:03:19Z

Here is the simple method to loop a method continuously

//create a handler, override handle message of Handler
    private Handler myHandler = new Handler(){
    @Override
    public void handleMessage(Message msg) {

// do yo stuffs here like UI update etc. 

//create a new message since a message will be consumed once as it       //delivered by handler after the delay
    Message message = new Message();
    message.what = msg.what;
// send the new message with handler
    myHandler.sendMessageDelayed(message, 150);
// 150 is time in milliseconds after which handler will give callback
    }
    };

// let us call the handler on touch of the view, set ontouch listener to //your desired view //on action down of on touch of the view, create a new message and pass it //to the handler

 @Override
    public boolean onTouch(View v, MotionEvent event) {
    switch(event.getAction()){
    case MotionEvent.ACTION_DOWN:
    Message message = new Message();
    myHandler.sendMessage(message);
    break;

// on action up of on touch of the view, remove the messages and call backs
//case MotionEvent.ACTION_UP:
    myHandler.removeCallbacksAndMessages(null);
    break;
    }
    return false;
    }

Apollo · Accepted Answer · 2015-02-05 09:39:42Z

1

change your starting function from

public void schedulePeriodicMethod() {
    exHandler.postDelayed(execution, 100);
}

to

public void schedulePeriodicMethod() {
    exHandler.post(execution);
}

and your runnable to :

private Runnable execution = new Runnable() {
    @Override
    public void run() {
        if (broadcastmode ==0) return;
        connectDevice(flag);
        serialSend("C");
        flag++;
        if (flag > 4)
            flag = 2;
        //call the runnable itself again, to keep execution going
        exHandler.postDelayed(execution, 100);
    }
};

And, as SGal said, your Thread.sleep is totally useless (btw, Thread.sleep in Android is not a good practice, especially on UI Thread)

answered Feb 5, 2015 at 9:39

Apollo

1961 silver badge9 bronze badges

2 Comments

YM Lam Over a year ago

Yeah. this method works. Thanks! It executes too fast, so i made the execution interval bigger. But if i need to wait for a certain event to trigger before executing/looping again, how can i do it?

Apollo Over a year ago

set a condition on the recall. But if you have multiple conditions for looping, maybe you don't really need a loop but an on wanted execution? so just delete the recall & call schedulePeriodicMethod() when you want to.

Yazan · Accepted Answer · 2015-02-05 09:20:55Z

0

i think schedulePeriodicMethod(); will call this one time:

public void schedulePeriodicMethod() {
        exHandler.postDelayed(execution, 100);
}

postDelayed() will run one time, so you need to recall it from the method itself

public void schedulePeriodicMethod() {
        exHandler.postDelayed(execution, 100);
        schedulePeriodicMethod();
}

answered Feb 5, 2015 at 9:20

Yazan

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3 Comments

YM Lam Over a year ago

tried calling the method again, app crashes once i press the button

Yazan Over a year ago

can you post the stacktrace plz

SGal Over a year ago

ofcource! silly me. postDelayed is not blocking, you probably get stack overflow exception. You should call the method from your runnable, but I see @Apollo already posted the correct answer

K Guru · Accepted Answer · 2015-02-05 09:28:15Z

this is because MotionEvent.ACTION_DOWN and MotionEvent.ACTION_MOVE Fire simultaneously when you Press the Button ,Use this approach

MOVE_THRESHOLD_DP = 20 * getActivity().getResources()
                .getDisplayMetrics().density;
    @Override
                public boolean onTouch(View v, MotionEvent event) {
                    // TODO Auto-generated method stub
                    final int action = event.getAction();
                    switch (action) {
                    case MotionEvent.ACTION_DOWN:
                        Log.d("TAG", "ON Down" + onMoveOccur);
                        onMoveOccur = false;
                        mDownPosX = event.getX();
                        mDownPosY = event.getY();

                      //your code 
                        break;
                    case MotionEvent.ACTION_UP:
                        Log.d("TAG", "ON UP==" + onMoveOccur);

                        if (!onMoveOccur) {
                            //your code 
                        }
                        break;

                    case MotionEvent.ACTION_MOVE:
                        if (Math.abs(event.getX() - mDownPosX) > MOVE_THRESHOLD_DP
                                || Math.abs(event.getY() - mDownPosY) > MOVE_THRESHOLD_DP) {
                            onMoveOccur = true;
                        }
                        break;

                    default:
                        break;
                    }

                    return false;
                }
            });

SGal · Accepted Answer · 2015-02-05 09:30:19Z

0

Remove thread sleeping, because it doesn't do anything here and at best makes app skip 6 frames and at worst might even crash some devices since it stops main thread for 100ms

try {
    Thread.sleep(100);
} catch (InterruptedException e) {
    e.printStackTrace();
}

And make shadulePeriodicMethod() call it self like

public void schedulePeriodicMethod() {
        exHandler.postDelayed(execution, 100);
        if (broadcastmode == 1){
            schedulePeriodicMethod();
        }
}

answered Feb 5, 2015 at 9:30

SGal

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1 Comment

YM Lam Over a year ago

tried calling the method itself. app crashes once i press the button

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