How to retrieve data from Firebase database without listeners?

Question

Right now I'm developing an android app, and I just started to work with Firebase.

My question is: How can I retrieve data from the firebase database, without use listeners ?

In my game, I'm saving the high scores of all the users, and I need to take the data from the database when user go into "leader-boards" page.

I saw some solutions, which is not good for my case. One of them is:

mRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String value = dataSnapshot.getValue(String.class);
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    });

This solution is not good for me, because I cant afford to my app to go into the server every time high score of user is changing, because if I would have 20,000 people who playing at the same time, then the game will stuck.

so I cant use this listener, because it will make the game very slow.

My goal is to to find a way to change the high score, without alerting the other people who is currently playing the game, I mean that I need to update every user score for his own, and when user go to the "leader boards" page, only then I will go to the server.

what is the right solution here ?

Or can I use this listener in another way?

If my question is not clear, then ask me in the comment please.

Thank you !!

my lines:

 public static void setUserHighScoreToServer(Context context,boolean isClassic,int scoreNum)
{
    com.firebase.client.Firebase mRef;
    mRef= new com.firebase.client.Firebase("...");
    String name = InternalStorage.getUserName(context);
    String classic = "";
    if(isClassic)classic="Classic";
    else classic="Arcade";
    com.firebase.client.Firebase mRefChild = mRef.child(name+classic);
    mRefChild.setValue(String.valueOf(scoreNum));


}

I do not have a real structure. I only have some lines of code, that put the high score of each user. Then the only thing I need to do with firebase is to retrieve them. I will add my single lines. — Levi Omer, Sep 03 '17 at 21:31
Happy to hear that, then please accept my answer and upvote it. — sabsab, Sep 09 '17 at 22:52
https://stackoverflow.com/questions/46135828/how-to-access-the-start-of-the-applicationnot-the-activity — Levi Omer, Sep 09 '17 at 23:03

score 3 · Accepted Answer · edited Sep 04 '17 at 00:18

3

This is the OFFICIAL way to retrieve data once without listening for data changes.

 // Add all scores in ref as rows 

scores.addListenerForSingleValueEvent( new ValueEventListener() { 
    @Override 
    public void onDataChange(DataSnapshot snapshot) {
        for (DataSnapshot child : snapshot.getChildren()) { 
            ... 
        } 
    }
}

more information here: https://firebase.google.com/docs/reference/android/com/google/firebase/database/DataSnapshot

edited Sep 04 '17 at 00:18

Angel Koh

12,479
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answered Sep 03 '17 at 23:50

sabsab

1,073
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Thank you !! So when is this listener will be called ? I need him to be called when I open specific activity. Can I do this ? – Levi Omer Sep 04 '17 at 00:24
Yes, just put it in the oncreate function – sabsab Sep 04 '17 at 09:50

score 1 · Answer 2 · answered Sep 03 '17 at 21:53

1

If you don´t need to update on real time, you can always do a Rest api call to your database. Just do a GET call to retrieve your data

https://[PROJECT_ID].firebaseio/[path].json

and you are good to go You can also update or create new keys using rest api calls.

answered Sep 03 '17 at 21:53

hacksy

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I did not understand. Can you explain ? or give me link to explanation ? – Levi Omer Sep 03 '17 at 21:57
You can check more info here https://firebase.google.com/docs/reference/rest/database/ – hacksy Sep 03 '17 at 22:03

How to retrieve data from Firebase database without listeners?

2 Answers2