Java – how to track listeners in firebase on Android?

I have a list of chat rooms for a given user in one location and the total number of messages for a given chat room in another location I want to track some messages in the chat room where users are

I have the following clips:

//getting all chat rooms this user belongs to
mFirebase.child("myChatRooms").child("testUser").addChildEventListener(new ChildEventListener() {
    @Override
    public void onChildAdded (DataSnapshot dataSnapshot,String prevIoUsKey){
        for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
            ChatRoom myRoom = postSnapshot.getValue(ChatRoom.class);

            //listening to  message count in every chat room user belongs to
            mFirebase.child("chatRoomMessageCount").child(postSnapshot.getKey()).addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                        //number of messages have changed
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) {

                }
            });
        }
    }

    //......
}

The question is, how can onchildremoved be called after deleting all these valueeventlisteners, or do I no longer need them?

What is the recommended way to deal with this situation? Should I store subkeys and listeners in the HashMap and track them myself, or are there ways to delete all listeners at a given firebase location?

Solution

The way to get serious data is to create a HashMap of valueeventlisteners, and then delete these listeners in onstop or ondestroy

To keep things simple, you should use a single event listener to get rooms Then, for each room, you can create a live listener

public class MainActivity extends Activity {

    private Firebase mRef;
    private HashMap<Firebase,ValueEventListener> mListenerMap;

    @Override
    protected void onStart() {
        super.onStart();

        mRef = new Firebase("https://<your-firebase-app>/myChatRooms/testUser");

        mRef.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {

                    ValueEventListener listener = new ValueEventListener() {
                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {
                            // do your thing here
                        }

                        @Override
                        public void onCancelled(FirebaseError firebaseError) {

                        }
                    };
                    mListenerMap.put(postSnapshot.getRef(),listener);
                    Firebase childRef = mRef.child("chatRoomMessageCount").child(postSnapshot.getKey());
                    childRef.addValueEventListener(listener);
                }
            }

            @Override
            public void onCancelled(FirebaseError firebaseError) {

            }
        });
    }

    @Override
    protected void onStop() {
        super.onStop();
        for (Map.Entry<Firebase,ValueEventListener> entry : mListenerMap.entrySet()) {
            Firebase ref = entry.getKey();
            ValueEventListener listener = entry.getValue();
            ref.removeEventListener(listener);
        }
    }
}