ListView load more at scroll begin

Question

I'm trying to implement some chat activity. Messages must be ordreded from older to newest (new messages on a bottom, older on a top of my ListView), for that i'm using android:transcriptMode="alwaysScroll" and android:stackFromBottom="true" on my layout. When user scroll to up ListView should be updated from older messages from my SQL database. Here is some code:

 public void onLoadFinished(Loader loader, Object data) {
 final Cursor cursor = (Cursor)data;
 if(cursor.getCount() > API_REQUEST_COUNT) {
 this.lsView.setStackFromBottom(false);
 }
 this.mAdapter.changeCursor(cursor);
 if(this.mAdapter.getCount() > 0) {
 this.isLoading = false; 
 }, 500);
 }
 }

And this is how i implement Load More function:

 this.lsView.setOnScrollListener(new AbsListView.OnScrollListener() {
 @Override
 public void onScrollStateChanged(AbsListView view, int scrollState) {
 }
 @Override
 public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
 int currentItemPosition = totalItemCount - firstVisibleItem;
 // TODO without refreshing cache :-(
 if(totalItemCount == 0 && !isLoading) {
 isLoading = true;
 if(getLoaderManager().getLoader(loaderId) != null) {
 getLoaderManager().restartLoader(loaderId, getArguments(), ConversationFragment.this);
 } else {
 getLoaderManager().initLoader(loaderId, getArguments(), ConversationFragment.this);
 }
 // TODO pagination
 ApiManager.getInstance().getDialog(dialogId, pageNum);
 }
 if(!isLoading && totalItemCount != 0 && currentItemPosition == (API_REQUEST_COUNT * pageNum) - 1) {
 pageNum++;
 ApiManager.getInstance().getDialog(dialogId, pageNum);
 }
 }
 });

The problem is, when i update my adapter ListView scroll to up, but i want that he freezes on a current position. Can anybody help?

Answer 1

after loading the New Data into Adpater this should work fine

 this.lsView.setSelection(this.mAdapter.getCount() - 1);

for that Try this,this will retain the scroll position

if(listView.getAdapter()==null)
 listView.setAdapter(this.mAdapter);
else{
 this.myAdapter.updateData(myNewData); //update your adapter's data
 this.myAdapter.notifyDatasetChanged();
}

• Yuriy Kolbasinskiy: Yes, this line should scroll to bottom my listview after update. But i want to stay on current position after update

Answer 2

use this,

listview.setOnScrollListener(new OnScrollListener() {
 @Override
 public void onScrollStateChanged(AbsListView view, int scrollState1) {
 // TODO Auto-generated method stub
 scrollState = scrollState1;
 isScrollCompleted();
 }
 @Override
 public void onScroll(AbsListView view, int firstVisibleItem1,
 int visibleItemCount1, int totalItemCount1) {
 // TODO Auto-generated method stub
 firstVisibleItem = firstVisibleItem1;
 visibleItemCount = visibleItemCount1;
 totalItemCount=totalItemCount1;
 }
 });

this is isScrollCompleted().

private void isScrollCompleted() {
 if(arrayList.size()>20)
 {
 Log.v("firstVisible", firstVisibleItem+"");
 Log.v("visibli", "item count"+visibleItemCount);
 Log.v("ScrollState", "scrollState"+scrollState);
 Log.v("total", totalItemCount+"");
 int lastInScreen=firstVisibleItem+visibleItemCount;
 if (lastInScreen == totalItemCount && scrollState == 0) {
 start=start+20;
 //get new twenty recornd in list and notify adapter
 cAdapter.notifyDataSetChanged();
 }
 }
 else
 {
 Log.v("arrayList", "size="+arrayList.size());
 }
 }

Answer 3

Store the firstVisible position item index at the time of more data loading (when reached at top of ListView). when data loaded successfully then set this value position to first Selected item using:-

setSelection(index);

If it not solve your problem Then let me know?

Answer 4

I run into the same problem. The solution that worked for me was before adding the new items to change the TranscriptMode:

listView.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_NORMAL);

After adding:

//inserted= number of inserted items
listView.setSelection(inserted+firstVisibleItem);

and in the onScrollStateChanged and onScroll I put the TranscriptMode back to the original:

if (inserted>0) {
listView.setTranscriptMode(AbsListView.TRANSCRIPT_MODE_ALWAYS_SCROLL);
inserted = 0;
}