按下按钮时如何继续添加？

Question

I'm building a simple counter, it has buttons to add or subtract from a total value, I want it to keep adding if I hold the button, incrementing +5 every second, but i'm having problems to make it work. I'm using onClickListener, but i can't find a way to make it work "together" with on touch listener.

pl.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {  
                lf++;            
                lt.setText(Integer.toString(lf));                
            }
        }

Answer 1

You will have to use handler to schedule a runnable that increments +5 every 1 second (+1 per 200 milliseconds to keep it smooth)

Handler handler = new Handler();
Runnable incrementTask = new Runnable(){
     @Override
     public void run(){
           lf++;
           handler.postDelayed(incrementTask, 200); //Execute after 200 milliseconds
      }
};

Then you implement onTouchListener and post this runnable when ACTION_DOWN is dispatched and cancel it when ACTION_UP is dispatched.

boolean buttonPressed = false;
pl.setOnTouchListener(new OnTouchListener() {

        @Override
        public boolean onTouch(View arg0, MotionEvent event) {
            if(event.getAction() == MotionEvent.ACTION_DOWN){

                 //This check is imporant since ACTION_DOWN might be called 
                 // multiple times when finger is moving
                  if(!buttonPressed){
                        buttonPressed = true;
                        handler.post(incrementTask);            
                   }
            } else if(event.getAction() == MotionEvent.ACTION_UP){
                  if(buttonPressed)
                   {
                      buttonPressed = false;
                      handler.cancel(incrementTask);
                   }
            }
            return false;
        }
    });

Please note that this logic won't work well with your current click listener. For better user experience, I would recommend that you start this timer/runnable only when your button is long pressed . I had a similar situation in a project so I wrote a utility class to help me detect when a button is being held and released after a long click. Normal clicks work fine as well. You can find my ClickAndHoldManager class on Github .

To use it, you simply pass your view in the constructor and set a listener:

ClickAndHoldManager manager = new ClickAndHoldManager(myButton);
manager.setClickCallback(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
             //Regular Click
            }
        });
manager.setHoldCallback(new ClickAndHoldManager.HoldListener() {
            @Override
            public void holdStarted() {
                // do handler.post() here
            }

            @Override
            public void holdEnded() {
                //do handler.cancel() here

            }
        });