Group items tagged

SizzlingSkizzorsProgrammer wrote: > After the listview is already initialized, is it possible to add items > to it during runtime? Just add the new items to the adapter, or the data source that backs up the adapter (if it's a CursorAdapter).

5 down vote accepted One solution is to implement an OnScrollListener and make changes (like adding items, etc.) to the ListAdapter at a convenient state in its onScrollStateChanged method. The following ListActivity shows a list of integers, starting with 40, adding 10 per scroll-stop.

public class Test extends ListActivity implements OnScrollListener {    Aleph0 adapter = new Aleph0();    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setListAdapter(adapter);         getListView().setOnScrollListener(this);    }    public void onScroll(AbsListView v, int i, int j, int k) { }    public void onScrollStateChanged(AbsListView v, int state) {        if(state == OnScrollListener.SCROLL_STATE_IDLE) {                adapter.count += 10;                adapter.notifyDataSetChanged();        }    }    class Aleph0 extends BaseAdapter {        int count = 40;        public int getCount() { return count; }        public Object getItem(int pos) { return pos; }        public long getItemId(int pos) { return pos; }        public View getView(int pos, View v, ViewGroup p) {                TextView view = new TextView(Test.this);                view.setText("entry " + pos);                return view;        }    }}

You should obviously use separate threads for long running actions (like loading web-data) and might want to indicate progress in the last list item (like the market or gmail apps do).

These applications use an OnScrollListener to detect when the last item is displayed. When this happens, they load more items and add them to the list adapter.