Firebase分页limitToFirst（）vs limitToLast（） [英] Firebase pagination limitToFirst() vs limitToLast()

问题描述

我试图在Android中实现Firebase，在这方面我有一些疑问，如果你能帮助我，我会很高兴。有点困惑。所以这是我的问题。

我在 listview 中显示Firebase聊天，其中我只想在该用户之后加载来自Firebase的第100封邮件将会执行 pull-to-refresh ，然后加载第一条200条消息，依此类推。

为此，我在 limitToFirst（）和 limitToLast（）不知道哪一个更好。

任何人都可以请求帮助。 ：

  int mPageEndOffset = 0; 
 int mPageLimit = 10; 
 
 @Override 
 public void onCreate（Bundle savedInstanceState）{
 super.onCreate（savedInstanceState）; 
 getActivity（）。getWindow（）。setSoftInputMode（WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE）; 
 connectDetector = new ConnectDetector（getActivity（））; 
 if（connectDetector.getConnection（））{
 
 alanRef = new Firebase（firebaseURL）.child（EventChatActivity.SuperCateName +/+ eventDetail.getCategory_name（）+/+ eventDetail .getEvent_title（）+/+ EventChatActivity.eventID）.child（StadiumChat）; 
 alanQuery = alanRef.limitToFirst（mPageLimit）; 
 userName = MyApp.preferences.getString（MyApp.USER_NAME，null）; 
 
 EventChatActivity.eventID）.child（StadiumChat）; 
 
 
 
 
 
 
 
这将从firebase中获取最新的10条消息的记录。  
I was trying to implement Firebase in android, I have few queries in that, I would be glad if you would help me into this. Getting bit confused in it. So here is my question. 

I am showing Firebase chat in listview in which I want to only load 1st 100 messages from firebase after that User will do pull-to-refresh then load 1st 200 messages and so on.



For that I am looking in limitToFirst() and limitToLast() not getting idea which one is better. 

Can anyone please help.
解决方案
You can try this way:
int mPageEndOffset = 0;
int mPageLimit = 10;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE);
    connectDetector = new ConnectDetector(getActivity());
    if(connectDetector.getConnection()) {

        alanRef = new Firebase(firebaseURL).child(EventChatActivity.SuperCateName + "/ " + eventDetail.getCategory_name() + "/ " + eventDetail.getEvent_title() + "/ " + EventChatActivity.eventID).child("StadiumChat");
        alanQuery = alanRef.limitToFirst(mPageLimit);
        userName = MyApp.preferences.getString(MyApp.USER_NAME, null);

        EventChatActivity.eventID).child("StadiumChat");
    }
}    
This will fetch records of latest 10 messages from firebase.

                        
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