Tukukkk

I am working on an android application, and I am using Firebase database,
this database showing an Items list.

This is my code.

private DatabaseReference root;

ListView elementList;

ArrayAdapter<mdlItem> adapter;

ArrayList<mdlItem> itemsList;

Context context;



private void loadFireDataBase() {

    root = FirebaseDatabase.getInstance().getReference().child("Offers");

    root.addChildEventListener(new ChildEventListener() {

        @Override

        public void onChildAdded(DataSnapshot dataSnapshot, String s) {

            Add_Chat(dataSnapshot, "Add");

        }



        @Override

        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

            Add_Chat(dataSnapshot, "Edit");

        }



        @Override

        public void onChildRemoved(DataSnapshot dataSnapshot) {

            Add_Chat(dataSnapshot , "Delete");

        }



        @Override

        public void onChildMoved(DataSnapshot dataSnapshot, String s) {



        }



        @Override

        public void onCancelled(DatabaseError databaseError) {





        }

    });

}



@Override

public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    //Log.i(tag, "onCreateView");

    return creatList(inflater, container);

}



private View creatList(LayoutInflater inflater, @Nullable ViewGroup container) {

    loadFireDataBase();

    context = getActivity();

    itemsList = new ArrayList<mdlItem>();

    View view;

    view = inflater.inflate(R.layout.freg_main_content, container, false);

    elementList = (ListView) view.findViewById(R.id.customListView);

    Collections.sort(itemsList, new Comparator<mdlItem>() {

        @Override

        public int compare(mdlItem data1, mdlItem data2) {

            if (data1.getOfferIndex() > data2.getOfferIndex())

                return 1;

            else

                return 0;

        }

    });

    adapter = new offersArrayAdapter(context, R.layout.item_list_layout, itemsList);

    elementList.setAdapter(adapter);

    elementList.setOnItemClickListener(this);

    return view;

}



private void Add_Chat(DataSnapshot dataSnapshot, String theCase) {

    Map<String, Object> question = null;

    try {

        String theOfferCode = dataSnapshot.getKey();

        question = (Map<String, Object>) dataSnapshot.getValue();

        mdlItem mdl = new mdlItem();

        mdl.setOfferCode(theOfferCode);

        mdl.setRestCode(Integer.parseInt(String.valueOf(question.get("itemCode"))));

        mdl.setRestName(question.get("itmeName").toString());

        switch (theCase) {

            case "Add":

                itemsList.add(mdl);

                break;

            case "Delete":

                itemsList.remove(mdl);

                break;

            case "Edit":

                //??

                break;

        }

        adapter.notifyDataSetChanged();

    } catch (Exception ex) {

        Toast.makeText(context, ex.getMessage(), Toast.LENGTH_LONG).show();

    }

}

The problem is I can't get any node index through 'dataSnapshot' object, to control the list when I make Delete and Update.

And another thing how to use Add_Chat method to add the mdl item in the top of other items list.

I already catch the Edit, delete and add in the database root but I can't control how to use these events in the right way

I think I need to get the 'dataSnapshot' object to remove it or set an update on it, or if there is another solution

Can any one help me in this.

Firebase snapshots are not index-based. If you need a mapping from the key in the database to the index in your adapter, you will need to maintain this mapping yourself.

For a simple version of this, have a look at the FirebaseArray class in the FirebaseUI library. It maintains a list of all snapshots that are currently in the array:

private final List<DataSnapshot> mSnapshots = new ArrayList<>();

And then in the onChildAdded methods adds, determines where the new item fits in the list and adds it:

public void onChildAdded(@NonNull DataSnapshot snapshot, @Nullable String previousChildKey) {

    int index = 0;

    if (previousChildKey != null) {

        index = getIndexForKey(previousChildKey) + 1;

    }



    mSnapshots.add(index, snapshot);

    notifyOnChildChanged(ChangeEventType.ADDED, snapshot, index, -1);

}

It does the equivalent for all other onChild... methods, so that it can look up the index for a specific key when needed with its getIndexForKey method:

private int getIndexForKey(@NonNull String key) {

    int index = 0;

    for (DataSnapshot snapshot : mSnapshots) {

        if (snapshot.getKey().equals(key)) {

            return index;

        } else {

            index++;

        }

    }

    throw new IllegalArgumentException("Key not found");

}

Just For recording, This is the correct solution

  int index = -1;

            for (mdlItem item: itemsList) {

                if (item.getIndex() == mdl.getIndex()) {

                    index = itemsList.indexOf(item);

                }

            }