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Query mSeenRef = db.child("Messages").child(MessageSenderId).child(MessageRecieverId).orderByChild("From").equalTo(MessageRecieverId);

    mSeenRef.addListenerForSingleValueEvent(new ValueEventListener(){

        @Override

        public void onDataChange(DataSnapshot dataSnapshot){

            if(dataSnapshot.exists()) {

                for (DataSnapshot ds : dataSnapshot.getChildren()) {

                    String keyId = ds.getKey();







                    DatabaseReference mSendersRef = db.child("Messages").child(MessageSenderId).child(MessageRecieverId).child(keyId);

                    DatabaseReference mRecieversRef = db.child("Messages").child(MessageRecieverId).child(MessageSenderId).child(keyId);

                    Map<String, Object> childUpdates = new HashMap<>();

                    childUpdates.put("Seen", true);

                    mSendersRef.updateChildren(childUpdates);

                    mRecieversRef.updateChildren(childUpdates);



                }

            }

        }

        @Override

        public void onCancelled(DatabaseError databaseError) {

        }

    });

This method turns a specific child called seen to true in my firebase database... I want to get the count of the number of childs which isnt true yet before turning into true... how can i achieve that... I want to execute a method just before turing it into true so i need the count

Database

If you want to know how many items the value of your Seen property true, please use the following lines of code:

Query mSeenRef = db.child("Messages").child(MessageSenderId).child(MessageRecieverId).orderByChild("Seen").equalTo(true);

ValueEventListener valueEventListener = new ValueEventListener() {

    @Override

    public void onDataChange(DataSnapshot dataSnapshot) {

        int count = 0;

        for(DataSnapshot ds : dataSnapshot.getChildren()) {

            count = count + 1;

        }

        Log.d(TAG, String.valueOf(count)); //Will print the number of seen messages

    }



    @Override

    public void onCancelled(@NonNull DatabaseError databaseError) {

        Log.d(TAG, databaseError.getMessage()); //Don't ignore errors!

    }

};

mSeenRef.addListenerForSingleValueEvent(valueEventListener);

As you can see, you just simply need to count the number of occurrences.

Another approach would be to use dataSnapshot.getChildrenCount() which will return a value of type long, which actually represents the number of children that exist within the dataSnapshot object.