Android dynamic loading list view onScrollListener issues

Question

I have implemented a list view, every user scroll to bottom screen, it auto add new data to list view Once the scroll has completed, onScroll() call for every new item that enters the displaying view, from the beginning to the end of the scrolling.

lv_best = (ListView) findViewById(R.id.lv_best);
bestadapter = new LazyAdapter(this, lst_tab_best);
lv_best.setAdapter(bestadapter);
lv_best.setOnScrollListener(new AbsListView.OnScrollListener() {

    @Override
    public void onScrollStateChanged(AbsListView view, int scrollState) { }

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

    Log.d("onScroll ", firstVisibleItem+"-"+visibleItemCount+"-"+totalItemCount);
    boolean loadMore = firstVisibleItem + visibleItemCount >= totalItemCount;
    if(loadMore){
            new ChangeTab_best().execute();
     }
     }
    });

I run in emulator, list above display with 5 items but I can't detect the end of scrolling in a ListView, ChangeTab_best() is called many time.When I see Logcat android , all variables firstVisibleItem,visibleItemCount,totalItemCount always equal 0

So what's happen here?

score 15 · Accepted Answer · answered Dec 07 '12 at 16:11

15

To detect the item at the bottom of the screen you have to work with firstVisibleItem and visibleItemCount. I had created a demo example for the same using AsyncTask that will loading items in background and update the UI.

Total of firstVisibleItem and visibleItemCount will give you the number of items that are loaded and then you can implement the logic of loading more items.

int loadedItems = firstVisibleItem + visibleItemCount;

answered Dec 07 '12 at 16:11

Lalit Poptani

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1

What about reverse Scrolling? – Pratik Butani May 05 '14 at 05:04

score 1 · Answer 2 · answered Apr 18 '13 at 08:50

The above implementaion may cause errors at edge conditions. The sum of first visible item & items in page may be 1 count more or less than expected. I was using the same thing untill i switched to a new method. What i did was implemented a listener to the Adapter of listview and in the getview check if(position== totalItemCount of items in array to be displayed), if yes i call up my listener from adapter. Quite simple

Veaceslav Gaidarji · Answer 3 · 2015-05-19T11:25:27.483

    lv_best.setOnScrollListener(new OnScrollListener() {
                @Override
                public void onScrollStateChanged(AbsListView view, int scrollState) {
                    switch (scrollState) {
                    case OnScrollListener.SCROLL_STATE_IDLE:
                                         // when list scrolling stops

                                        manipulateWithVisibleViews(view);

                        break;
                    case OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:
                        break;
                    case OnScrollListener.SCROLL_STATE_FLING:
                        break;
                    }
                }

                @Override
                public void onScroll(AbsListView view, int firstVisibleItem,
                        int visibleItemCount, int totalItemCount) { 
                }
            });

private void manipulateWithVisibleViews(AbsListView view){
        int count = view.getChildCount(); // visible views count
        int lastVisibleItemPosition = view.getLastVisiblePosition();

        for (int i = 0; i < count; i++) {
            View convertView = view.getChildAt(i);
            // update views
            }
        }

}

firstVisibleItem,visibleItemCount,totalItemCount still equal 0, and list view loaded 5 items.I can't detect last visible item — chinh, Dec 07 '12 at 15:18
how to load server data using pagenation to listview android with existing data — Harsha, May 19 '15 at 10:40

Android dynamic loading list view onScrollListener issues

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