how to maintain scroll position of listview when it updates

Question

I have read plenty of examples ,but if I wish to maintain my scroll position after a ListView is updated from JSON ,then can I do that without using an

Answer 1

If you're using an ArrayAdapter (or a subclass of it), the problem may be caused by that the adapter updates the list when you clean it before adding the new items:

adapter.clear();
adapter.addAll(...);

You can fix it by wrapping the code that modifies the adapter like this:

adapter.setNotifyOnChange(false); // Disable calling notifyDatasetChanged() on modification
adapter.clear();
adapter.addAll(...); // Notify the adapter about that data has changed. Note: it will re-enable notifyOnChange
adapter.notifyDataSetChanged();

Answer 2

For overall picture:

In your API response callback, call this function(example) below:

MyAdapter mAdapter;
ArrayList<Users> mUsers;

private void updateListView(ArrayList<Users> users) {
    mUsers.addAll(users);
    if(mAdapter == null) {
        mAdapter = new MyAdapter(getContext(), mUsers);
        mListView.setAdapter(mAdapter);
    }
    mAdapter.notifyDataSetChanged(); // Add this one
}

Answer 3

listview.setSelection( i );

this will help you to set particular row at top

Answer 4

It is easier to maintain scroll position by calling notifydatasetchanged() only. The problem there is that you are creating a new adapter every time the data gets updated... you should do something like this:

if(listView.getAdapter()==null)
   listView.setAdapter(myAdapter);
else{
   myAdapter.updateData(myNewData);  //update adapter's data
   myAdapter.notifyDataSetChanged(); //notifies any View reflecting data to refresh
}

This way, your listview will mantain the scrolling position.

In case you want to scroll to a new position, use:

list.smoothScrollToPosition(int position);

Answer 5

list.smoothScrollToPosition(int position);     //my favorite :)

It may also help you to scroll nice'n'smooth to a particular item

Answer 6

In case for some reason you don't want to call notifyDataSetChanged(), the you can maintain the position by using setSelectionFromTop()

Before updating the adaptor:

lastViewedPosition = listView.getFirstVisiblePosition();

//get offset of first visible view
View v = listView.getChildAt(0);
topOffset = (v == null) ? 0 : v.getTop();

After updating the adaptor:

listView.setSelectionFromTop(lastViewedPosition, topOffset);