Android - Samsung issue - ListView fast scrolling with double drag

Question

Today I noticed that when you do a quick double drag in a ListView, the list will go to the end or the beginning of the list. It appears that this only happens in Samsung phones.

This has become an issue because I am adding JazzyListView animation effects to the elements on the list and they crash whenever this quick movement happens. (NullPointerException whenever the ListView.layoutChildren method is invoked)

Maybe I will need to modify the library, or is it any way to disable this ListView behavior?

Answer 1

Well this effect is called "DOUBLE FLING", it appears in logcat whenever I do it, unfortunately in AbsListView the only thing you can do about flinging is setting friction and velocity scale. If someone knows how to disable the effect it would be great (However that may not be the best solution for this problem, as the users may be familiar with that behavior)

What I did (my quick + dirty solution) was to modify the JazzyListView library, specifically JazzyHelper class, only validating that the item is not null before applying animation:

           while (firstVisibleItem + indexAfterFirst < mFirstVisibleItem) {
                View item = view.getChildAt(indexAfterFirst);
                if(item != null) {
                    doJazziness(item, firstVisibleItem + indexAfterFirst, -1);
                }

                indexAfterFirst++;
            }

            int indexBeforeLast = 0;
            while (lastVisibleItem - indexBeforeLast > mLastVisibleItem) {
                View item = view.getChildAt(lastVisibleItem - firstVisibleItem - indexBeforeLast);

                if(item != null) {
                    doJazziness(item, lastVisibleItem - indexBeforeLast, 1);
                }

                indexBeforeLast++;

            }

I believe that I should modify something about instance property mFirstVisibleItem, else the fastscrolling removes the animation on displaying items. However, my solution works for anyone who wants to quickly solve this issue.