Android Firebase滚动时加载更多数据

Question

我正在使用以下示例（数据库）来练习我的Android开发技能。

https://github.com/firebase/quickstart-android/tree/master/database

当我滚动到帖子列表的底部时，我想实现一个自动加载更多功能。如何在MyPostsFragment中初始查询后加载更多数据？这是我的代码：我在recyclerview上添加了一个scrolllistener，当它到达列表的底部时，我的函数loadData（）查询

PostListFragment.java：

  private final int THREAT_SHOT = 5;
  mRecycler.setAdapter(mAdapter);
  mRecycler.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
            super.onScrollStateChanged(recyclerView, newState);
        }

        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);

            if( mManager.getItemCount() - THREAT_SHOT == mManager.findLastVisibleItemPosition() - 1){
                loadMoreData();

            }
        }
    });

}

private void loadMoreData() {


    mDatabase.child("user-posts").child(getUid()).orderByKey().startAt(oldestPostId).limitToFirst(5).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot child : dataSnapshot.getChildren()) {
                oldestPostId = child.getKey(); ////HERE WE ARE SAVING THE LAST POST_ID FROM URS POST

            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

}

MyPostsFragment.java：

@Override
public Query getQuery(DatabaseReference databaseReference) {
    // All my posts
    return databaseReference.child("user-posts").child(getUid()).orderByKey().limitToFirst(5);

}