Custom ListView with Custom Filtering (Mono for Android)

Activity.cs

// grab input field to filter with
EditText etFilter = FindViewById(Resource.Id.studentFilter);

// call custom adapter filter method on TextChange
etFilter.TextChanged += delegate(object sender, Android.Text.TextChangedEventArgs e)
{
        adapter.filterStudents(e.Text.ToString());
};

BaseAdapterImplementation.cs

internal class StudentListAdapter : BaseAdapter
{
    private List orig_items;
    private List items;
    private StudentList outer_context;

    public StudentListAdapter(Context context, List items)
    {
        this.orig_items = items;
        this.items = items;
        this.outer_context = (StudentList) context;
    }

    public override View GetView(int position, View convertView, ViewGroup parent)
    {
        //inflate the custom view
        LayoutInflater vi = 
            (LayoutInflater)outer_context.GetSystemService(Context.LayoutInflaterService);

        View v = vi.Inflate(Resource.Layout.ItemStudent, null);

        /*
            TODO - Populate View
        */

        return v;
    }

    /***
     * Custom Basic Filtering Function
     */
    public void filterStudents(string filter)
    {
        // Create new empty list to add matched elements to
        IList filtered = new List();
        
        // examine each element to build filtered list
        // remember to always use your original items list
        foreach (Student s in this.orig_items)
        {
            string name = s.ToString();
            if (name.Contains(filter))
            {
                filtered.Add(s);
            }
        }
        
        //set new (filterd) current list of items
        this.items = filtered;
        
        //notify ListView to Rebuild
        NotifyDataSetChanged();
    }

    public override Student this[int position]
    {
        get { return this.items[position]; }

    }

    public override int Count
    {
        get { return items.Count; }
    }

    public override long GetItemId(int position)
    {
        return position;
    }
}