retrieve data from firebase realtime database code example

Example 1: used to retrieve dat from firebase realtime datastore

var playersRef = firebase.database().ref("players/");

playersRef.on("child_added", function(data, prevChildKey) {
   var newPlayer = data.val();
   console.log("name: " + newPlayer.name);
   console.log("age: " + newPlayer.age);
   console.log("number: " + newPlayer.number);
   console.log("Previous Player: " + prevChildKey);
});

Example 2: firebase realtime database store array

The Firebase Database doesn't store arrays. It stores dictionaries/associate arrays. So the closest you can get is:

attendees: {
  0: "Bill Gates",
  1: "Larry Page",
  2: "James Tamplin"
}

Example 3: firebase realtime database read data

If you want to get a specific data using a phone number then you can use a Query like this

DatabaseReference database = FirebaseDatabase.getInstance().getReference();
DatabaseReference ref = database.child("profiles");

Query phoneQuery = ref.orderByChild(phoneNo).equalTo("+923336091371");
phoneQuery.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot singleSnapshot : dataSnapshot.getChildren()){
           user = singleSnapshot.getValue(User.class); 
        }
    }
    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.e(TAG, "onCancelled", databaseError.toException());
    }
});
I think this is the best method.