RecyclerView 移除或解除附加事件

Question

对于这个简单问题，我非常感谢您的帮助和指导。

RecyclerView layout

我有一个包含电影列表的 RecyclerView。我想创建一个动态列表，可以从目录中添加一些电影。

问题是，当我为按钮单击添加事件时，由于 holder 被绑定了几次，所以该事件被附加了几次。我不知道如何使用 SetOnClickListener 技术，因为我需要 holder.AdapterPosition 来知道应该在哪里添加新项目。我将它作为附加项传递给 MovieCatalogActivity，然后将其发送回包含 RecyclerView 的 activity。

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using AndroidX.RecyclerView.Widget;
using Java.Util;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Supers.Adapters
{
    public class adap_rv : RecyclerView.Adapter
    {
        public List<ItemMovies> data;
        Context context;
        public adap_rv(List<ItemMovies> listOfMovies, Context _context)
        {
            data = listOfMovies;
            context = _context;
        }

        public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
        {
            View itemView = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.elem_ReviewMovies, parent, false);
            ViewHolderRR vh = new ViewHolderRR(itemView);
            return vh;
        }

        public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
        {
            ViewHolderRR vh = holder as ViewHolderRR;


            vh.imAddBefore.Click += delegate
            {
                ShowMovieCatalog(holder.AdapterPosition);
            };
            vh.imAddAfter.Click += delegate
            {
                ShowMovieCatalog(holder.AdapterPosition + 1);
            };


            vh.tvName.Text = data[position].Name;


        }




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


        public void OnItemMove(int fromPosition, int toPosition)
        {
            data.Swap(fromPosition, toPosition);
            NotifyItemMoved(fromPosition, toPosition);

        }

        public void OnItemDismiss(int position)
        {
            data.RemoveAt(position);
            NotifyItemRemoved(position);

        }

        public void AddItem(int position, ItemMovies movie)
        {
            if (position > data.Count)
            {
                data.Add(movie);
            }
            else
            {
                data.Insert(position, movie);
            }

            NotifyItemInserted(position);
        }

        void ShowMovieCatalog(int position)
        {
            Intent intent = new Intent(context, typeof(Act_frmMovieCatalog));
            intent.PutExtra(Enums.INTENTEXTRAS.INT_POSITIONITEM.ToString(), position);
            ((Activity)context).StartActivityForResult(intent, 100);
        }

    }

    public class ViewHolderRR : RecyclerView.ViewHolder
    {
        public TextView tvName { get; private set; }
        public ImageButton imAddBefore { get; private set; }
        public ImageButton imAddAfter { get; private set; }
        public ViewHolderRR(View itemView) : base(itemView)
        {
            imAddBefore = itemView.FindViewById<ImageButton>(Resource.Id.elem_btnAddBefore);
            imAddAfter = itemView.FindViewById<ImageButton>(Resource.Id.elem_btnAddAfter);
        }

    }
}

也许如果我从 ViewHolder 内部监听事件，但我找不到示例。

Answer 1

如果想在item布局中点击Button时添加新的Item，可以参考下面的代码：

public override void OnBindViewHolder(RecyclerView.ViewHolder holder, int position)
        {
            ViewHolderRR vh = holder as ViewHolderRR;

           // vh.imAddBefore.Click += delegate
           //{
           //    ShowMovieCatalog(holder.AdapterPosition);
           //};

           // other code

           vh.imAddBefore.SetOnClickListener(new MyAddItemBefore(position));

        }

MyAddItemBefore.cs（Photo是我的物品型号，你可以换成你的）

   class MyAddItemBefore : Java.Lang.Object, View.IOnClickListener
    {
        Photo item;
        int position;
        public MyAddItemBefore( int position) {
            this.item=  new Photo();
            this.position = position;
        }

        public void OnClick(View v)
        {
            item.mCaption = "test";
            data.Insert(position, item);

            adapter.NotifyDataSetChanged();
        }
    }

注：

imAddAfter以类似的方式实现。

如果您想 return position 到您的 activity，您可以在 RecyclerView.Adapter 中添加一个 EventHandler(adap_rv ).

 public event EventHandler<int> ItemClick;

 // Raise an event when the item-click takes place:
    void OnClick(int position)
    {
        if (ItemClick != null)
            ItemClick(this, position);
    }

并且在方法中OnCreateViewHolder

    public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup parent, int viewType)
    {
        View itemView = LayoutInflater.From(parent.Context).Inflate(Resource.Layout.elem_ReviewMovies, parent, false);

        // pass `OnClick` to Your ViewHolder
        ViewHolderRR vh = new ViewHolderRR(itemView,OnClick);
        return vh;
    }

在你的 ViewHolderRR.cs

     public ViewHolderRR(View itemView, Action<int> listener) : base(itemView)
    {
        // other code
        imAddBefore = itemView.FindViewById<Button>(Resource.Id.AddBeforeBtn);

        // Detect user clicks on the item view and report which item
        // was clicked (by layout position) to the listener:
        imAddBefore.Click += (sender, e) => listener(base.LayoutPosition);

 }

在您的 activity 中，添加以下代码：

    // mAdapter is the instance of your RecyclerView.Adapter (`adap_rv `)
    mAdapter.ItemClick += OnItemClick;


    void OnItemClick(object sender, int position)
    {
        int itemNum = position + 1;

        System.Diagnostics.Debug.WriteLine("clicked position = " + itemNum);
    }

RecyclerView 移除或解除附加事件

RecyclerView remove or deattach event

c#

xamarin.android