Removing Fragments from ViewPager

DummyFragment.cs

public class DummyFragment : Fragment
{
    public override View OnCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        var view = inflater.Inflate(Resource.Layout.dummy_frag, container, false);
        var tv = view.FindViewById<TextView>(Resource.Id.textView1);
        tv.Text = "" + Arguments.GetInt("number", -1);
        return view;
    }
}

Main.axml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <android.support.v4.view.ViewPager
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/viewPager" />
</LinearLayout>

MainActivity.cs

[Activity(Label = "App2", MainLauncher = true, Icon = "@drawable/icon")]
public class MainActivity : FragmentActivity
{
    private ViewPager _viewPager;
    private ViewPagerAdapter _adapter;

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);

        _viewPager = FindViewById<ViewPager>(Resource.Id.viewPager);
        _adapter = new ViewPagerAdapter(this, _viewPager, SupportFragmentManager);
        _viewPager.Adapter = _adapter;
    }

    public override bool OnCreateOptionsMenu(IMenu menu)
    {
        base.OnCreateOptionsMenu(menu);
        MenuInflater.Inflate(Resource.Menu.menu, menu);
        return true;
    }

    public override bool OnOptionsItemSelected(IMenuItem item)
    {
        switch (item.ItemId)
        {
            case Resource.Id.action_add_fragment:
                _adapter.AddFragment(typeof(DummyFragment));
                break;
            case Resource.Id.action_remove_fragment:
                _adapter.RemoveFragment(_adapter.Count - 1);
                break;
        }

        return base.OnOptionsItemSelected(item);
    }
}

menu.xml

<?xml version="1.0" encoding="utf-8" ?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
  <item android:id="@+id/action_add_fragment"
        android:title="@string/action_add_fragment"
        android:showAsAction="ifRoom|withText"/>
  <item android:id="@+id/action_remove_fragment"
        android:title="@string/action_remove_fragment"
        android:showAsAction="ifRoom|withText"/>
</menu>

strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <string name="action_add_fragment">Add</string>
  <string name="action_remove_fragment">Remove</string>
</resources>

ViewPagerAdapter.cs

public class ViewPagerAdapter : FragmentStatePagerAdapter
{
    private class ViewPagerItem
    {
        public Type Type { get; set; }
        public Fragment CachedFragment { get; set; }
    }

    private readonly Context _context;
    private readonly ViewPager _viewPager;
    private readonly Dictionary<int, ViewPagerItem> _fragments = new Dictionary<int, ViewPagerItem>();

    public ViewPagerAdapter(IntPtr javaReference, JniHandleOwnership transfer) 
        : base(javaReference, transfer) { }

    public ViewPagerAdapter(Context context, ViewPager pager, FragmentManager fm)
        : base(fm)
    {
        _context = context;
        _viewPager = pager;
    }

    public override Fragment GetItem(int position)
    {
        if (!_fragments.ContainsKey(position)) return null;

        var bundle = new Bundle();
        bundle.PutInt("number", position);
        _fragments[position].CachedFragment = Fragment.Instantiate(_context,
            FragmentJavaName(_fragments[position].Type), bundle);
        return _fragments[position].CachedFragment;
    }

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

    public void AddFragment(Type fragType, int position = -1)
    {
        if (position < 0 && _fragments.Count == 0)
            position = 0;
        else if (position < 0 && _fragments.Count > 0)
            position = _fragments.Count;

        _fragments.Add(position, new ViewPagerItem
        {
            Type = fragType
        });

        NotifyDataSetChanged();
    }

    public void RemoveFragment(int position)
    {
        DestroyItem(null, position, _fragments[position].CachedFragment);
        _fragments.Remove(position);
        NotifyDataSetChanged();
        _viewPager.SetCurrentItem(position - 1, false);
    }

    protected virtual string FragmentJavaName(Type fragmentType)
    {
        var namespaceText = fragmentType.Namespace ?? "";
        if (namespaceText.Length > 0)
            namespaceText = namespaceText.ToLowerInvariant() + ".";
        return namespaceText + fragmentType.Name;
    }
}

HI, trying to use this but it's not working. When i try to add a fragment i get error message saying that MyNameSpace.FragmentClassName can not be found. I replace this line _fragments[position].CartFragment = Fragment.Instantiate(_context, FragmentJavaName(_fragments[position].Type), bundle); by _fragments[position].CartFragment = CartFragment.NewInstance(); and it works, but then, remove doesn't works. The removed fragment still on screen. Thanks.

Found out why removing is not working, this is missing:

public override int GetItemPosition (Java.Lang.Object objectValue)
{
return PagerAdapter.PositionNone;
}

Still not finding solution for class not found, but it is working with my own line of code.

Thanks.