Question

我有一个Grid RecyclerView（3列），我在OnBindViewHolder方法中添加了一个委托点击监听器。

场景（附加日志）

假设我有18个项目，即6行。默认情况下没有任何滚动，我只能看到2.5行。

当我点击项目（位置0-8）时，委托函数只被调用一次（尝试1~2）。

当我滚动到页面末尾，然后单击其中一个项目时，委托函数将被调用一次（尝试3）。

如果我向上滚动，然后单击其中一个项目，委托函数将被调用4次（尝试4）。

在我的（尝试5）中，我将其滚动到底部并单击一个项目，这次，委托函数被调用两次。

注意：

我正在使用Xamarin.Android
我只点击了那些项目
我已经使用多个设备进行了测试并获得了相同的结果
调用的委托函数数量不固定，有时每次点击最多可调用6次。

我的问题是为什么会发生这种情况，还有其他正确的方法来实现吗？

日志

// Attempt 1 : (I clicked position 1)
[[Log ==== ]] [Time : 9/12/2015 10:36:44 AM ] Clicked position [1]
// Attempt 2 : (I clicked position 3)
[[Log ==== ]] [Time : 9/12/2015 10:36:52 AM ] Clicked position [3]
// Attempt 3 : (I scroll it till the end of the page and clicked position 14)
[[Log ==== ]] [Time : 9/12/2015 10:36:52 AM ] Clicked position [14]
// Attempt 4 : (I scroll it back to the top and clicked position 1)
[[Log ==== ]] [Time : 9/12/2015 10:40:08 AM ] Clicked position [4]
[[Log ==== ]] [Time : 9/12/2015 10:40:08 AM ] Clicked position [15]
[[Log ==== ]] [Time : 9/12/2015 10:40:08 AM ] Clicked position [5]
[[Log ==== ]] [Time : 9/12/2015 10:40:08 AM ] Clicked position [16]
[[Log ==== ]] [Time : 9/12/2015 10:40:08 AM ] Clicked position [1]
// Attempt 5 : (I scroll it down again and clicked position 14)
[[Log ==== ]] [Time : 9/12/2015 10:41:57 AM ] Clicked position [11]
[[Log ==== ]] [Time : 9/12/2015 10:41:57 AM ] Clicked position [14]

活动

[Activity (Label = "DrinksMenuCategory", Theme = "@style/AppTheme.ActionBar")]          
public class DrinksMenuCategory : AppCompatActivity
{
    private RecyclerView mRecyclerView;
    private RecyclerView.LayoutManager mLayoutManager;
    private RecyclerView.Adapter mAdapter;

    private int selected_drinksCategory;
    private List<Drinks> drinksCategory;

    protected override void OnCreate (Bundle bundle)
    {
        base.OnCreate (bundle);
        SetContentView (Resource.Layout.Activity_DrinksMenuCategoryGridview);
        SupportActionBar.SetDisplayHomeAsUpEnabled (true);

        mRecyclerView = FindViewById<RecyclerView> (Resource.Id.recyclerView_drinksMenuCategoryGridView);
        mRecyclerView.HasFixedSize = true;

        mLayoutManager = new GridLayoutManager (this, 3);
        mRecyclerView.SetLayoutManager (mLayoutManager);
        mAdapter = new DrinksMenuCategoryRecyclerAdapter (drinksCategory, mRecyclerView);
        mRecyclerView.SetAdapter (mAdapter);
    }
}

适配器＆amp; ViewHolder

public class DrinksMenuCategoryRecyclerAdapter : RecyclerView.Adapter
{
    public List<Drinks> mDrinksItems;
    public RecyclerView mRecyclerView;

    public DrinksMenuCategoryRecyclerAdapter (List<Drinks> drinksItems, RecyclerView mRecyclerView)
    {
        this.mDrinksItems = drinksItems;
        this.mRecyclerView = mRecyclerView;
    }

    public override int GetItemViewType (int position)
    {
        return Resource.Layout.recyclerView_cell_drinksMenu_category;
    }

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

        CardView v_drinksCard = row.FindViewById<CardView> (Resource.Id.drinks_card);
        ImageView v_drinksImage = row.FindViewById<ImageView> (Resource.Id.drinks_image);
        TextView v_drinksText = row.FindViewById<TextView> (Resource.Id.drinks_text);

        DrinksMenuItemHolder viewHolder = new DrinksMenuItemHolder (row, parent.Context) {
            mDrinksCard = v_drinksCard,
            mDrinksImage = v_drinksImage,
            mDrinksText = v_drinksText
        };

        return viewHolder;
    }

    public override void OnBindViewHolder (RecyclerView.ViewHolder holder, int position)
    {
        DrinksMenuItemHolder viewHolder = holder as DrinksMenuItemHolder;
        viewHolder.mDrinksCard.Click += delegate {
            // *** Click Event ***
            Log.Debug ("[DrinksMenuCategoryRecyclerAdapter ==== ]", "[Time : " + DateTime.Now + " ] Clicked position [" + position + "]");
            Toast.MakeText (viewHolder.context, "[Time : " + DateTime.Now + " ] Clicked position [" + position + "]", ToastLength.Short).Show (); 
        };
        viewHolder.mDrinksText.Text = mDrinksItems[position].name;
    }

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

    public class DrinksMenuItemHolder : RecyclerView.ViewHolder
    {
        public Context context { get; set; }
        public View mMainView { get; set; }

        public CardView mDrinksCard { get; set; }
        public ImageView mDrinksImage { get; set; }
        public TextView mDrinksText { get; set; }

        public DrinksMenuItemHolder (View view, Context context) : base (view)
        {
            this.context = context;
            mMainView = view;
        }
    }
}

Answer 1

（我知道我迟到了，但无论如何......）

viewHolder.mDrinksCard.Click += delegate {..}

每次绑定ViewhHolder（发生很多事情）时，您都会创建一个新委托并将其添加到潜在的现有视图中。随着时间的推移，视图会累积多个Click个代表，每个代表依次响应一次点击。

您需要断开连接，删除Click中的Adapter.onViewRecycled()代理。

RecyclerView.OnBindViewHolder点击多次被调用？

1 个答案: