Firebase retrieving the child value from realtime database of Firebase

Question

I am new to Firebase and Android. I have stored user authentication details (name, profile image other than email ID) in my Firebase account. I want to retrieve those data (such as names etc.,) to the other part of my app. How can I retrieve my realtime database child values?

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http://stackoverflow.com/questions/27848313/firebase-retrieve-child-android?rq=1 — GoneUp, Nov 23 '16 at 15:35
https://firebase.google.com/docs/database/android/read-and-write — JP Ventura, Nov 23 '16 at 16:13

score 3 · Accepted Answer · answered Nov 23 '16 at 15:37

final FirebaseDatabase database = FirebaseDatabase.getInstance();
DatabaseReference ref = database.getReference("userID").child("displayName");

// Attach a listener to read the data at our posts reference
ref.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String displayName = dataSnapshot.getValue().toString();
        System.out.println(displayName );
    }

For more: Read and Write Data on Android - Firebase Documentation

dataSnapshot.getValue().toString(); goes to an error.called=method 'java.lang.String java.lang.Object.toString()' on a null object reference — Athul Antony NP, Nov 24 '16 at 04:04

score 2 · Answer 2 · answered Nov 23 '17 at 23:28

If you want to get the names of all the users, then you can do it like this

DatabaseReference mRef = FirebaseDatabase.getInstance().getReference();

        mRef.child("users").addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for(DataSnapshot snapshot: dataSnapshot.getChildren()){
                    Log.v("user_name", snapshot.getValue(String.class));
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

Firebase retrieving the child value from realtime database of Firebase

2 Answers2