Question

I know the title is somewhat confusing, my problem is this: I want to “pause” my program multiple times (via a loop) using sleep(ms) and make changes to several buttons that the user has pressed. I understand that changes to the UI can only be made in the main thread, so I am wondering how to convert this code into an Async task. I also remember reading somewhere that Async task can only be called once? If this is so, what other solutions could I look into?

View.OnClickListener SimulateButtonHandler = new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        for(int j=0;j<169;j++) //169 buttons to click
        {
            if(ClickedPoints[j]!=null) //how I keep track of which buttons has clicked
            {       //clear button color
                Drawable d2 = ClickedPoints[j].getBackground();  
                ClickedPoints[j].invalidateDrawable(d2);  
                d2.clearColorFilter();
            }

        }

        Timer timer = new Timer();

        for(int i=0;i<169;i++)
        {
            if(ClickedPoints[i]!=null)
            {       //change the color after some time
                Simulate(timer, i);
                //clear color again
                Drawable d2 = ClickedPoints[i].getBackground();  
                ClickedPoints[i].invalidateDrawable(d2);  
                d2.clearColorFilter();

            }

        }
}   
};

public void Simulate(Timer timer, final int index)
{
    timer.schedule(new TimerTask()
    {
        public void run() {
            Sim(index);
        }

    }, 1000); //delay for some amount of time, then rehighlight the button
}

private void Sim(int i)
{
    Drawable d1 = ClickedPoints[i].getBackground();  
    PorterDuffColorFilter filter = new PorterDuffColorFilter(Color.RED, PorterDuff.Mode.SRC_ATOP);  
    d1.setColorFilter(filter);
}

Answer 1

You’d be better off using a Thread to run your background work (and pausing) and a Handler to access the UI thread.

Here’s a good tutorial on using handlers with threads.