Android List OnScrollListener how to detect everytime a new List item is visible in either direction

Question

Learning how to use the OnScrollListener and I want to make a way I can detect everytime a new List item is visible when a user scrolls up or down in a listview, if the user scrolls down I want to make a counter increment by 1 for each new cell that enters the screen and if it scrolls up I want it to decrement, any help would go a long way, thanks.

counter = 0;
    list.setOnScrollListener(new OnScrollListener() {
        public void onScrollStateChanged(AbsListView view, int scrollState) {

        }

        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {

            // If list scroll up
            counter++;

            // If list scrolls down
            counter--;

        }
    });

Or should something like this be done in the list adapter instead? — Edmund Rojas, Dec 20 '12 at 21:27
Isn't the `firstVisibleItem` more or less the number you want? — Henry, Dec 20 '12 at 21:37
what should I use to determine if its a new view however? should I say if(firstVisibleItem > ) ? — Edmund Rojas, Dec 20 '12 at 21:52

score 3 · Answer 1 · answered Dec 21 '12 at 00:04

I figured it out, the first visible item increments by one as you scroll down

counter = 0;
    list.setOnScrollListener(new OnScrollListener() {
        public void onScrollStateChanged(AbsListView view, int scrollState) {
            // Do nothing
        }

        public void onScroll(AbsListView view, int firstVisibleItem,
                int visibleItemCount, int totalItemCount) {

            if(firstVisibleItem > counter + 3 || firstVisibleItem < counter - 3){
                counter = firstVisibleItem;
                Toast.makeText(ListTestActivity.this,
                        "counter = " + counter,
                        Toast.LENGTH_LONG).show();
            }



        }
    });

score 1 · Answer 2 · answered Dec 20 '12 at 21:43

1

Use the firstVisibleItem variable. When it changes, adjust your count appropriately.

answered Dec 20 '12 at 21:43

Khantahr

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what should I compare firstvisibleitem against to determine if a new view is visible in either direction? – Edmund Rojas Dec 20 '12 at 21:50
Make a private class variable that holds the last visible item and compare it with `firstVisibleItem` every time `onScroll` is called. If they're different, update your private variable with the new visible item and adjust your counter. – Khantahr Dec 20 '12 at 21:54

Android List OnScrollListener how to detect everytime a new List item is visible in either direction

2 Answers2