Navigation Drawer: Add Titles to Groups, Not Items

Question

I have a standard Navigation Drawer, pre-created by Android Studio and want to populate it with number of groups. I started with this:

Answer 1

add xml class navigation_drawer_title:

and change your navigationAdapter like this

private static final int TYPE_HEADER = 0; 
    private static final int TYPE_ITEM = 1;
    private static final int TYPE_SEPARATOR = 2;
    private static final int TYPE_TITLE = 3;
    @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
        {
            View v = null;
            switch (viewType)
            {
                case TYPE_HEADER:
                    v = LayoutInflater.from(parent.getContext()).inflate(R.layout.navigation_drawer_header, parent, false); //Inflating the layout
                    break;
                case TYPE_ITEM:
                    v = LayoutInflater.from(parent.getContext()).inflate(R.layout.navigation_drawer_item, parent, false); //Inflating the layout
                    break;
                case TYPE_SEPARATOR:
                    v = LayoutInflater.from(parent.getContext()).inflate(R.layout.navigation_drawer_separator, parent, false); //Inflating the layout
                    break;

                case TYPE_TITLE:
                    v = LayoutInflater.from(parent.getContext()).inflate(R.layout.navigation_drawer_title, parent, false); //Inflating the layout
                    break;
            }
            return new ViewHolder(v, viewType); // Returning the created object

        }

and

@Override
    public int getItemViewType(int position)
    {
        if (position == 0)
            return TYPE_HEADER;
        if (navMenuItems.get(position - 1).getItemType() == NavItemType.Group)
            return TYPE_SEPARATOR;
        if (navMenuItems.get(position - 2).getItemType() == NavItemType.Group)
            return TYPE_TITLE

        return TYPE_ITEM;
    }