I want to get item in the last node added in firebase database from my Android. You can see on the image below i\'m not sure how to get the specific node, because unique key
This might work:
DatabaseReference db = FirebaseDatabase.getInstance().getReference().child("mp");
Query query = db.orderByKey().limitToLast(1);
query.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot child: dataSnapshot.getChildren()) {
            Log.d("User key", child.getKey());
            Log.d("User val", child.child("message").getValue().toString());
        } 
    }
    @Override
    public void onCancelled(DatabaseError databaseError) {
        // TODO: Handle errors.
    }
});