Question

我在Visual Studio 2017上使用RecyclerView（Xamarin.Android），这是我的第一个Xamarin项目，因为我是一名原生的Android开发人员，而且我对于实施On Items Clicks事件感到困惑。 Recycler View。我刚刚使用IDE提供的默认模板（RecyclerAdapter类）创建了RecyclerView.Adapter，它看起来很像本机实现：

这是我的代码：

using System;
using Android.Views;
using Android.Widget;
using Android.Support.V7.Widget;

namespace Airlink
{
    class PdfAdapter : RecyclerView.Adapter
    {
        public event EventHandler<PdfAdapterClickEventArgs> ItemClick;
        public event EventHandler<PdfAdapterClickEventArgs> ItemLongClick;
        Pdf[] items;

        public PdfAdapter(Pdf[] data)
        {
            items = data;
        }

        // Create new views (invoked by the layout manager)            
        public override RecyclerView.ViewHolder OnCreateViewHolder(ViewGroup   
        parent, int viewType)
        {

            //Setup your layout here
            View itemView = null;
            //var id = Resource.Layout.__YOUR_ITEM_HERE;   
            itemView=LayoutInflater.From(parent.Context).
            Inflate(Resource.Layout.pdf_item, parent, false);  


            var vh = new PdfAdapterViewHolder(itemView, OnClick, 
            OnLongClick);
            return vh;
        }

        // Replace the contents of a view (invoked by the layout manager)
        public override void OnBindViewHolder(RecyclerView.ViewHolder 
        viewHolder, int position)
        {
            var item = items[position];

            // Replace the contents of the view with that element
            PdfAdapterViewHolder holder = viewHolder as 
            PdfAdapterViewHolder;
            holder.pdf_name.Text = items[position].Name;
        }

        public override int ItemCount => items.Length;

        void OnClick(PdfAdapterClickEventArgs args) => 
        ItemClick?.Invoke(this, args);
        void OnLongClick(PdfAdapterClickEventArgs args) => 
        ItemLongClick?.Invoke(this, args);

    }

    public class PdfAdapterViewHolder : RecyclerView.ViewHolder
    {
        public TextView pdf_name { get; set; }


        public PdfAdapterViewHolder(View itemView, 
            Action<PdfAdapterClickEventArgs> clickListener,
            Action<PdfAdapterClickEventArgs> longClickListener) : 
        base(itemView)
        {
            pdf_name = itemView.FindViewById<TextView>
            (Resource.Id.pdf_name);
            itemView.Click += (sender, e) => clickListener(new 
            PdfAdapterClickEventArgs { View = itemView, Position = 
            AdapterPosition });
            itemView.LongClick += (sender, e) => longClickListener(new 
            PdfAdapterClickEventArgs { View = itemView, Position = 
            AdapterPosition });
        }
    }

    public class PdfAdapterClickEventArgs : EventArgs
    {
        public View View { get; set; }
        public int Position { get; set; }


    }
}

所以，鉴于我的代码，我只是想知道在哪里可以处理点击的视图，我不确定是否必须在PdfAdapterClickEventArgs类或接收PdfAdapterClickEventArgs对象的OnClick和OnLongClick空洞上实现一些代码，假设我想显示一个Toast，显示View中单击的TextView的名称。我使用以下方法在原生Android上处理此操作：

  view.setOnClickListener(new View.OnClickListener() {

      @Override
      public void onClick(View v) {        

         //my code here
      }
  }

在ViewHolder构造函数方法中。

我的意思是，我可以更改默认的C＃实现，以获得类似于上面代码段的内容，但我想保留原始的C＃代码。

Answer 1

您将在Activity / Fragment中实现OnClick事件处理程序，其中创建了Adapter的实例。

此行表示您正在适配器类中公开ItemClick事件。

public event EventHandler<PdfAdapterClickEventArgs> ItemClick;

所以你现在能够做到这一点：

var adapter = new PdfAdapter(data);
adapter.ItemClick += OnItemClick;
   ....
   ....
myRecyclerView. SetAdapter(adapter);

你将有一个方法：

public void OnItemClick(object sender, PdfAdapterClickEventArgs e)
{
   var view = args.View; //this is your view
   Toast.MakeText(this, $"Item Position: {args?.Position}", ToastLength.Short).Show();
}

希望这有帮助。

RecyclerView.ViewHolder点击项目

1 个答案: