ArrayIndexOutOfBoundsException throws while Thread is working normally

Question

I'm using Thread to set color to a list of ImageView one by one after time of Thread.sleep. It works normally but after few loops of Thread, my app is stop working and throws ArrayIndexOutOfBoundsException.

private Runnable runnable = new Runnable() {

        int position = 0;

        @Override
        public void run() {
            while (true) {
                if (position >= MAX_ITEM) {
                    position = 0;
                }
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        for (int i = 0; i < itemIndicators.size(); i++) {
                            itemIndicators.get(i).setSelected(false);
                        }
                        if (position >= 0){
                            itemIndicators.get(position-1).setSelected(true);
                        }
                    }
                });

                position++;

                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

        }
    };

My list's size is the same number to MAX_ITEM. Please help me out of this. Thanks so much!

Are you sure itemIndicators is size MAX_ITEM? You really should be using itemIndicators.size() instead. And make sure itemIndicators is something that can be accessed asycnhronously safely. — Gabe Sechan, May 23 '19 at 15:46
yeah, I will keep your words for the next time. Thank you so much for helping xD — Bin Ky, May 23 '19 at 16:02

score 1 · Answer 1 · answered May 23 '19 at 15:39

1

If position is 0 you're accessing item at index -1

if (position >= 0) {
    itemIndicators.get(position-1).setSelected(true);
}

Remove the -1.

answered May 23 '19 at 15:39

Francesc

25,014
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score 1 · Accepted Answer · answered May 23 '19 at 15:46

1

your error is caused by this line

  if (position >= 0){
     itemIndicators.get(position-1).setSelected(true);
   }

you should edit your condition to position > 0 to avoid getting get(-1)

answered May 23 '19 at 15:46

ismail alaoui

5,748
2
21
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ArrayIndexOutOfBoundsException throws while Thread is working normally

2 Answers2