在 RecyclerView 中更改可绘制对象会更新所有行

Question

我正在尝试在我的应用程序中获取 'like' 按钮功能，就像在 Facebook 中一样。我想要的是，每当用户点击“赞”按钮时，按钮上可绘制对象的颜色应该从灰色变为蓝色。我正在使用 RecyclerView 作为提要。由于 RecyclerView 强制使用 viewholder 模式，所有类似按钮的颜色此后都会更改。我真的很感激能帮我解决这个问题。

这是适配器的代码

public class FacebookTimelineAdapter : RecyclerView.Adapter
{
    Context mContext { get; set;}
    List<FacebookModel> mData;
    LayoutInflater inflater;
    FacebookViewHolder holder;

    public FacebookTimelineAdapter (Context context,List<FacebookModel> data)
    {
        this.mContext = context;
        this.mData = data;
        this.inflater = LayoutInflater.From (context);
    }

    #region implemented abstract members of Adapter
    public override void OnBindViewHolder (RecyclerView.ViewHolder viewholder, int position)
    {
        holder = viewholder as FacebookViewHolder;
        holder.userName.Text = mData [position].userName;
        holder.timestamp.Text = mData [position].timestamp;

        if(!(mData[position].profilePictureId==0) || !(mData[position].profilePictureId==null))
        holder.profilePicture.SetImageDrawable (mContext.Resources.GetDrawable(mData[position].profilePictureId));

        if (mData [position].feedMessage == "") {
            holder.feedMessage.Visibility = ViewStates.Gone;
        } else {
            holder.feedMessage.Visibility = ViewStates.Visible;
            holder.feedMessage.Text = mData [position].feedMessage;
        }


        if ((mData [position].feedUrl == "") || (mData [position].feedUrl ==null)) {
            holder.feedUrl.Visibility = ViewStates.Gone;
        } else {
            holder.feedUrl.Visibility = ViewStates.Visible;
            holder.feedUrl.Text = mData [position].feedUrl;
        }

        if ((mData [position].feedImage==null) || (mData [position].feedImage==0)) {
            holder.feedImage .Visibility = ViewStates.Gone;
        } else {
            holder.feedImage .Visibility = ViewStates.Visible;
            holder.feedImage.SetImageDrawable(mContext.Resources.GetDrawable(mData[position].feedImage)) ;
        }

        holder.like.Click += delegate {
            Drawable img = mContext.Resources.GetDrawable (Resource.Drawable.fb_comment);
            holder.like.SetCompoundDrawablesWithIntrinsicBounds (img, null, null, null);
        };



    }

    public override RecyclerView.ViewHolder OnCreateViewHolder (ViewGroup parent, int viewType)
    {

        return new FacebookViewHolder (inflater.Inflate (Resource.Layout.timeline_item_facebook,parent,false),this);

    }


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

    public void LikeClicked(int position)
    {
        Drawable img = mContext.Resources.GetDrawable (Resource.Drawable.fb_comment);
        holder.like.SetCompoundDrawablesWithIntrinsicBounds (img, null, null, null);

    }
    #endregion
}
}

这是 ViewHolder 的代码

    public class FacebookViewHolder : RecyclerView.ViewHolder
    {
        public TextView userName,timestamp,feedUrl,feedMessage;
        public ImageView profilePicture,feedImage;
        public Button like, comment;


        public FacebookViewHolder(View item, FacebookTimelineAdapter adapter) : base(item)
        {
            userName=item.FindViewById<TextView>(Resource.Id.fb_userName);
            timestamp=item.FindViewById<TextView>(Resource.Id.fb_time);
            feedUrl=item.FindViewById<TextView>(Resource.Id.fb_feed_url);
            feedMessage=item.FindViewById<TextView>(Resource.Id.fb_feed_message);
            profilePicture=item.FindViewById<ImageView>(Resource.Id.fb_profilePicture);
            feedImage=item.FindViewById<ImageView>(Resource.Id.fb_feed_image);
            like=item.FindViewById<Button>(Resource.Id.fb_feed_like);
            comment=item.FindViewById<Button>(Resource.Id.fb_feed_comment);

        }

    }

代码在 C# 中，因为我正在 Xamarin 中开发 android 应用程序。

Answer 1

使用回收视图模式时，您应该'reset'将回收视图的状态恢复到其初始状态，这样您就不会在回收视图时将对一个子项所做的更改应用到另一个子项。

Answer 2

我在某种程度上解决了 Marcos 提供的解决方案。

这是我的适配器

public class FacebookTimelineAdapter : RecyclerView.Adapter
{
    Context mContext { get; set;}
    List<FacebookModel> mData;
    LayoutInflater inflater;
    FacebookViewHolder holder;

    public FacebookTimelineAdapter (Context context,List<FacebookModel> data)
    {
        this.mContext = context;
        this.mData = data;
        this.inflater = LayoutInflater.From (context);
    }

    #region implemented abstract members of Adapter
    public override void OnBindViewHolder (RecyclerView.ViewHolder viewholder, int position)
    {
        holder = viewholder as FacebookViewHolder;
        holder.userName.Text = mData [position].userName;
        holder.timestamp.Text = mData [position].timestamp;

        if(!(mData[position].profilePictureId==0) || !(mData[position].profilePictureId==null))
        holder.profilePicture.SetImageDrawable (mContext.Resources.GetDrawable(mData[position].profilePictureId));

        if (mData [position].feedMessage == "") {
            holder.feedMessage.Visibility = ViewStates.Gone;
        } else {
            holder.feedMessage.Visibility = ViewStates.Visible;
            holder.feedMessage.Text = mData [position].feedMessage;
        }


        if ((mData [position].feedUrl == "") || (mData [position].feedUrl ==null)) {
            holder.feedUrl.Visibility = ViewStates.Gone;
        } else {
            holder.feedUrl.Visibility = ViewStates.Visible;
            holder.feedUrl.Text = mData [position].feedUrl;
        }

        if ((mData [position].feedImage==null) || (mData [position].feedImage==0)) {
            holder.feedImage .Visibility = ViewStates.Gone;
        } else {
            holder.feedImage .Visibility = ViewStates.Visible;
            holder.feedImage.SetImageDrawable(mContext.Resources.GetDrawable(mData[position].feedImage)) ;
        }

  // Made changes in data structure to see if the post was liked or not. 

    if (mData [position].liked) {
            Drawable img = mContext.Resources.GetDrawable (Resource.Drawable.fb_liked);
            holder.like.SetCompoundDrawablesWithIntrinsicBounds (img, null, null, null);
        } else {
            Drawable img = mContext.Resources.GetDrawable (Resource.Drawable.fb_like);
            holder.like.SetCompoundDrawablesWithIntrinsicBounds (img, null, null, null);
        }

    }

    public override RecyclerView.ViewHolder OnCreateViewHolder (ViewGroup parent, int viewType)
    {

        return new FacebookViewHolder (inflater.Inflate (Resource.Layout.timeline_item_facebook,parent,false),this);

    }


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

 // On Clicking the like button notifyItemChanged() is called
    public void LikeClicked(int position)
    {
        if (mData [position].liked)
            mData [position].liked = false;
        else
            mData [position].liked = true;

        NotifyItemChanged (position);

    }

这是我的 ViewHolder

 public class FacebookViewHolder : RecyclerView.ViewHolder
    {
        public TextView userName,timestamp,feedUrl,feedMessage;
        public ImageView profilePicture,feedImage;
        public Button like, comment;


        public FacebookViewHolder(View item, FacebookTimelineAdapter adapter) : base(item)
        {
            userName=item.FindViewById<TextView>(Resource.Id.fb_userName);
            timestamp=item.FindViewById<TextView>(Resource.Id.fb_time);
            feedUrl=item.FindViewById<TextView>(Resource.Id.fb_feed_url);
            feedMessage=item.FindViewById<TextView>(Resource.Id.fb_feed_message);
            profilePicture=item.FindViewById<ImageView>(Resource.Id.fb_profilePicture);
            feedImage=item.FindViewById<ImageView>(Resource.Id.fb_feed_image);
            like=item.FindViewById<Button>(Resource.Id.fb_feed_like);
            comment=item.FindViewById<Button>(Resource.Id.fb_feed_comment);

           // Added Click listener in Viewholder
            like.Click += delegate {
                adapter.LikeClicked(LayoutPosition);
            }; 
        }

    }

在 RecyclerView 中更改可绘制对象会更新所有行

Changing drawable in RecyclerView updates all rows

android

android-recyclerview

android-viewholder