Xamarin Android：在上下文操作模式下单击后退按钮时，如何取消选择recyclerview行

Question

Hello everyone my name is Taniguchi.

I've made a recylerview and inserted a contextual action mode and i coded when there is no row selected the contextual action mode finishes.

But im having trouble when i click the back button of contextual action mode or i click on the back button on my phone when the contextual action mode is activated the rows stays selected.

My contextual action mode class:

 public class MyActionMode : Java.Lang.Object, ActionMode.ICallback
{

    private RecyclerViewHolder holder;
    private Context mContext;
    private RecyclerView.Adapter mAdapter;
    private int currentPosition;
    private Button button;
    public View v;
    public static bool ismenuactivated = true;
    private IMenu menu;
    private View menuItemView;
    private List<Email> mEmails;
    public CheckBox cbx;
    public View itemView;
    private RecyclerView mRecyclerView;

    public MyActionMode(Context context) : this(context, null, 0)
    {

    }

    public MyActionMode(Context context, RecyclerView.Adapter adapter, int position)
    {
        mContext = context;
        mAdapter = adapter;
        currentPosition = position;
    }

    public bool OnActionItemClicked(ActionMode mode, IMenuItem item)
    {

        switch (item.ItemId)
        {
            case Resource.Id.itemOneId:
                return true;
            case Resource.Id.itemTwoId:
                // do Update
                return true;
            default:
                return false;
        }
    }

    public bool OnCreateActionMode(ActionMode mode, IMenu menu)
    {
        mode.MenuInflater.Inflate(Resource.Menu.ContextualMenu, menu);
        //------------------------------------------

        button = (Button)menu.FindItem(Resource.Id.itemTwoId).ActionView;
        button.Background = null;
        var draw = ContextCompat.GetDrawable(mContext, Resource.Drawable.three_dots);
        button.SetCompoundDrawablesWithIntrinsicBounds(draw, null, null, null);
        button.Click += delegate {
            PopupMenu menu1 = new PopupMenu(mContext, button);
            menu1.Inflate(Resource.Menu.popup_menu);
            menu1.Show();
        };

        return true;
    }

    public void OnDestroyActionMode(ActionMode mode)
    {
        mode.Dispose();

    }

    public bool OnPrepareActionMode(ActionMode mode, IMenu menu)
    {
        return false;
    }
}

My RecyclerView Adapter:

public class RecyclerAdapter : RecyclerView.Adapter, View.IOnClickListener, View.IOnLongClickListener
{
    private View view;
    private Boolean isSelected = false;

    public Boolean IsSelected()
    {
        return isSelected;
    }

    public void setSelected(Boolean selected)
    {
        isSelected = selected;
    }

    private Activity mActivity;
    private MyActionMode mActionMode;
    private List<Email> mEmails;
    private Context context;
    private ActionMode mode;
    public bool count = false;
    public int CountAuxiliar = 0;
    public event EventHandler<int> ItemClick;
    public RecyclerAdapter(List<Email> emails, Context context)
    {
        mEmails = emails;
        this.context = context;
    }

    public RecyclerAdapter(List<Email> emails, Activity activity)
    {
        mEmails = emails;
        mActivity = activity;
    }
    public class MyView : RecyclerView.ViewHolder
    {
        public View mMainView { get; set; }
        public TextView mName { get; set; }
        public TextView mSubject { get; set; }
        public TextView mMessage { get; set; }

        public MyView(View view) : base(view)
        {
            mMainView = view;
        }

    }

    public override int ItemCount
    {
        get { return mEmails.Count; }
    }

    public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
    {
        LayoutInflater inflater = LayoutInflater.From(parent.Context);
        View row = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.row, parent, false);
        RecyclerViewHolder vh = new RecyclerViewHolder(row);
        return vh;
    }
    public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
    {
        RecyclerViewHolder myHolder = holder as RecyclerViewHolder;
        myHolder.cbx.Visibility = mEmails[position].IsSelected() ? ViewStates.Visible : ViewStates.Gone;
        myHolder.cbx.Checked = mEmails[position].IsSelected();
        if(MyActionMode.ismenuactivated == false){
            myHolder.cbx.Visibility = ViewStates.Gone;
        }

        myHolder.mName.Text = mEmails[position].Name;
        myHolder.mSubject.Text = mEmails[position].Subject;
        myHolder.mMessage.Text = mEmails[position].Message;


        myHolder.ItemView.SetBackgroundColor(mEmails[position].IsSelected() ? Color.LightBlue : Color.Transparent);
        myHolder.ItemView.Tag = position;
        myHolder.ItemView.SetOnClickListener(this);
        myHolder.ItemView.SetOnLongClickListener(this);
    }
    void View.IOnClickListener.OnClick(View v)
    {
        if (CountAuxiliar > 0 && mode != null)
        {
            int position = (int)v.Tag;
            mEmails[position].setSelected(!mEmails[position].IsSelected());
            v.SetBackgroundColor(mEmails[position].IsSelected() ? Color.LightBlue : Color.Transparent);
            v.FindViewById(Resource.Id.checkBox1).Visibility = mEmails[position].IsSelected() ? ViewStates.Visible : ViewStates.Invisible;
            if (mEmails[position].IsSelected())
            {
                CountAuxiliar++;
            }
            else
            {
                CountAuxiliar--;
            }
            mode.Title = CountAuxiliar.ToString() + " " + "Selecionados";
            Toast.MakeText(v.Context, "Click : " + CountAuxiliar + "---" + position, ToastLength.Short).Show();
        }
        if (CountAuxiliar < 1 && count == true)
        {
          count = false;
          mode.Finish();
          MainActivity.bottomnavigationview1.Visibility = ViewStates.Gone;
          MainActivity.floatinactionbutton1.Visibility = ViewStates.Visible;
        }
    }
    public bool OnLongClick(View v)
    {

        if (CountAuxiliar < 1)
        {
            CountAuxiliar = 1;
            count = true;
            int position = (int)v.Tag;
            mEmails[position].setSelected(!mEmails[position].IsSelected());
            v.SetBackgroundColor(mEmails[position].IsSelected() ? Color.LightBlue : Color.Transparent); MainActivity.bottomnavigationview1.Visibility = ViewStates.Visible;
            MainActivity.floatinactionbutton1.Visibility = ViewStates.Gone;
            v.FindViewById(Resource.Id.checkBox1).Visibility = mEmails[position].IsSelected() ? ViewStates.Visible : ViewStates.Invisible;
            mActionMode = new MyActionMode(mActivity, this, position);
            mode = mActivity.StartActionMode(mActionMode);
            mode.Title = CountAuxiliar.ToString() + " " + "Selecionado";
            count = true;

            Toast.MakeText(v.Context, "Long Click : " + mEmails[position].IsSelected() + "---" + position, ToastLength.Short).Show();
        }
        return true;
    }
}

My Click Listener:

public class RecyclerViewHolder : RecyclerView.ViewHolder
{
    public TextView mName;
    public TextView mSubject;
    public TextView mMessage;
    public CheckBox cbx;
    public Button bottonbutton;
    public int count = 0;
    private Action<object, View.LongClickEventArgs, int> onLongClick;

    public RecyclerViewHolder(View itemView) : base(itemView)
    {
        mName = itemView.FindViewById<TextView>(Resource.Id.textView1);
        mSubject = itemView.FindViewById<TextView>(Resource.Id.textView2);
        mMessage = itemView.FindViewById<TextView>(Resource.Id.textView3);
        cbx = itemView.FindViewById<CheckBox>(Resource.Id.checkBox1);
    }
}

I wonder how to unselect rows, the color went back to white when i click on the back button of the contextual action mode or click on the back button of the phone when the contextual action mode is activated.

Answer 1

You should deal with the logic in method OnDestroyActionMode when you press the back button on contextual action mode.

public void OnDestroyActionMode(ActionMode mode)
{
    mode.Dispose();
 //**** remove selection here  ***
    mAdapter.removeSelection();

}

And add function removeSelection in your RecyclerAdapter

public void removeSelection()
    {
        //here deal with your data and refresh UI.
         //assign all the value of `IsSelected` to false of mEmails list
        if (mEmails!=null ) {
           foreach (Email email in mEmails) {
              email.setSelected(false);
         }

        // refresh UI
        NotifyDataSetChanged();
    }