Question

我在我的应用中广泛使用了Firebase RecyclerViewAdapter，但由于下面的代码没有触发populateViewHolder而没有首先加载任何数据，我无法显示加载完成消息初始负荷

RecyclerView recycler = (RecyclerView) findViewById(R.id.messages_recycler);
recycler.setHasFixedSize(true);
recycler.setLayoutManager(new LinearLayoutManager(this));

mAdapter = new FirebaseRecyclerAdapter<Chat, ChatHolder>(Chat.class, android.R.layout.two_line_list_item, ChatHolder.class, mRef) {
    @Override
    public void populateViewHolder(ChatHolder chatMessageViewHolder, Chat chatMessage, int position) {
        chatMessageViewHolder.setName(chatMessage.getName());
        chatMessageViewHolder.setText(chatMessage.getText());
    }
};
recycler.setAdapter(mAdapter);

Answer 1

此功能涵盖了您所描述的内容：Handle empty state for recycleview。您可以通过在适配器中实现onDataChanged()来解决此问题。一个snippet from the sample app of FirebaseUI：

@Override
protected void onDataChanged() {
    // if there are no chat messages, show a view that invites the user to add a message
    mEmptyListView.setVisibility(
        mRecyclerViewAdapter.getItemCount() == 0 ? View.VISIBLE : View.INVISIBLE
    );
}

Answer 2

if（chatMessage.getName（）。equals（＆＃34;＆＃34;））{// null value} else { //执行代码}

Answer 3

覆盖onDataChanged（）并检入

jar

如何检测FirebaseRecyclerAdapter中存在的空值或子值

3 个答案: