@Override
public void onScroll(AbsListView absListView, int first, int visible, int total) {
    if (!isLoading && total < totalItemsInYourList) {
        if (first + visible >= total - 1) {
            loadNextPage();
        }
    }
}

// isLoading is a boolean that flags whether you're loading more data
// totalItemsInYourList is... the total number of items in your list
// loadNextPage() loads more data