Qfyilyi

Query ref = mDatabaseReference.child("Messages")

            .child(MessageRecieverId).child(MessageSenderId).orderByChild("Seen").equalTo(false);

    ref.addValueEventListener(new ValueEventListener() {

        @Override

        public void onDataChange(DataSnapshot dataSnapshot) {

            long count = 0;

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

                count = dataSnapshot.getChildrenCount();



                MainData helper = new MainData(getApplicationContext()); //Change the name to your Helper Class name

                SQLiteDatabase db = helper.getWritableDatabase();

                String newId = "MyData";

                Cursor data = helper.getData();

                long newDatar = 0;

                long newDatat = 0;

                while(data.moveToNext()){

                    newId = data.getString(data.getColumnIndex("Data"));

                    newDatar = data.getInt(data.getColumnIndex("TotalMessagesRecieved"));

                    newDatat = data.getInt(data.getColumnIndex("TotalMessages"));

                }

                ContentValues contentValues = new ContentValues();

                contentValues.put(KEY_DATA, newId);

                contentValues.put(KEY_TOTAL_MESSAGES_RECIEVED, (newDatar+count));

                contentValues.put(KEY_TOTAL_MESSAGES, (newDatat+count));//Change the value of newData(which is actually your old value) by incrementing

                long returnVariable = db.update(TABLE_MAIN_DATA, contentValues, null, null);



                if(returnVariable == -1){

                    Toast.makeText(getApplication(),"Nope", Toast.LENGTH_LONG).show();

                    //-1 means there was an error updating the values

                }

                else{

                    Toast.makeText(getApplication(),"r", Toast.LENGTH_SHORT).show();

                }

            }

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

        }



        @Override

        public void onCancelled(@NonNull DatabaseError databaseError) {

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

        }

    });

The problem with this is the first time i open the activity and if there is one child to be added to the table in sqlite it adds normally without any problem and then i close the activity and i open it again and it adds the child twice even if there is just one and if i close and open it again it adds thrice instead of one and it just goes on... So why is this behavious and how can i change it to executing just once like the first time i open the activity... And i cannot use valueforsingleevent as i need to listen to listener when im inside the activity every second... and the removelistener too didnt work while closing the activity... So someone please help me out

It's probable that you never removed the listener when the activity finished. You add a listener with ref.addValueEventListener(), but never remove it with ref.removeEventListener(). If you never remove a listener, it will continue to trigger with new changes. On Android, you typically make those call symmetrical, so if you add a listener during onStart, you would remove it during onStop.