为什么不RecyclerView有onItemClickListener（）？而如何RecyclerView从列表视图不同？ [英] Why doesn't RecyclerView have onItemClickListener()? And how RecyclerView is different from Listview?

问题描述

我不知道是否我问正确的问题。我正在研究 RecyclerView ，我很惊讶地看到， RecyclerView 没有 onItemClickListener（） 。因为 RecyclerView 扩展

I don't know whether I am asking the right question. I was exploring RecyclerView and I was surprised to see that RecyclerView does not have onItemClickListener(). Because RecyclerView extends

android.view.ViewGroup

和的ListView 扩展

android.widget.AbsListView

。不过，我写的onClick 在解决我的问题我的 RecyclerView.Adapter ：

. However I solved my problem by writing onClick in my RecyclerView.Adapter:

public static class ViewHolder extends RecyclerView.ViewHolder implements OnClickListener {

    public TextView txtViewTitle;
    public ImageView imgViewIcon;

    public ViewHolder(View itemLayoutView) {
        super(itemLayoutView);
        txtViewTitle = (TextView) itemLayoutView.findViewById(R.id.item_title);
        imgViewIcon = (ImageView) itemLayoutView.findViewById(R.id.item_icon);
    }

    @Override
    public void onClick(View v) {

    }
}

但我仍想知道为什么谷歌删除 onItemClickListener（）？

有性能问题或其他什么东西？

Is there a performance issue or something else?

推荐答案

TL;博士 <一个href="http://www.littlerobots.nl/blog/Handle-Android-RecyclerView-Clicks/">http://www.littlerobots.nl/blog/Handle-Android-RecyclerView-Clicks/

由于引入的ListView ， onItemClickListener 一直是个问题。那一刻，你有一个点击侦听器的任何内部元件的回调将不会被触发，但它并没有收到通知或有据可查（如果有的话），所以有很多的困惑和关于它的SO问题。

Since the introduction of ListView, onItemClickListener has been problematic. The moment you have a click listener for any of the internal elements the callback would not be triggered but it wasn't notified or well documented (if at all) so there was a lot of confusion and SO questions about it.

由于 RecyclerView 它采取了一步，没有一个行/列的概念，而是一个任意布置的孩子数量，他们已经委托onClick的为他们每个人，或者程序员的实现。

Given that RecyclerView takes it a step further and doesn't have a concept of a row/column, but rather an arbitrarily laid out amount of children, they have delegated the onClick to each one of them, or to programmer implementation.

想想 Recyclerview 的不作为的ListView 1：1替代，而是一种更灵活的组件，用于复杂的使用案例。正如你说的，你的解决方案是谷歌对你的期望。现在你有谁可以委托的onClick对构造通过一个接口，这是正确的模式为的ListView适配器和 Recyclerview 。

Think of Recyclerview not as a ListView 1:1 replacement but rather as a more flexible component for complex use cases. And as you say, your solution is what google expected of you. Now you have an adapter who can delegate onClick to an interface passed on the constructor, which is the correct pattern for both ListView and Recyclerview.

public static class ViewHolder extends RecyclerView.ViewHolder implements OnClickListener {

    public TextView txtViewTitle;
    public ImageView imgViewIcon;
    public IMyViewHolderClicks mListener;


    public ViewHolder(View itemLayoutView, IMyViewHolderClicks listener) {
        super(itemLayoutView);
        mListener = listener;
        txtViewTitle = (TextView) itemLayoutView.findViewById(R.id.item_title);
        imgViewIcon = (ImageView) itemLayoutView.findViewById(R.id.item_icon);
        imgViewIcon.setOnClickListener(this);
        itemLayoutView.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        if (v instanceof Imageview){
           mListener.onTomato((ImageView)v)
        } else {
           mListener.onPotato(v);
        }
    }

    public static interface IMyViewHolderClicks {
        public void onPotato(View caller);
        public void onTomato(ImageView callerImage);
    }

}

，然后您的适配器

and then on your adapter

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

   String[] mDataset = { "Data" };

   @Override
   public MyAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
       View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.my_layout, parent, false);

       MyAdapter.ViewHolder vh = new ViewHolder(v, new MyAdapter.ViewHolder.IMyViewHolderClicks() { 
           public void onPotato(View caller) { Log.d("Poh-tah-tos"); };
           public void onTomato(ImageView callerImage) { Log.d("To-m8-tohs"); }
        });
        return vh;
    }

    // Replace the contents of a view (invoked by the layout manager) 
    @Override 
    public void onBindViewHolder(ViewHolder holder, int position) {
        // Get element from your dataset at this position 
        // Replace the contents of the view with that element 
        // Clear the ones that won't be used
        holder.txtViewTitle.setText(mDataset[position]);

    } 

    // Return the size of your dataset (invoked by the layout manager) 
    @Override 
    public int getItemCount() { 
        return mDataset.length;
    } 

  ...

现在看看这最后一块code： onCreateViewHolder（ViewGroup中的父母，INT viewType）的签名已经提出不同的看法类型。对于他们中的每一个你会需要不同的viewholder过了，随后他们每个人可以有不同的设置的点击。或者你可以创建一个通用的viewholder可以接收任意视图，其中 onClickListener ，并付诸实践。或委托上一级的协调器等等几个片段/活动具有相同的列表中用不同的点击行为。同样，所有的灵活性就在你身边。

Now look into that last piece of code: onCreateViewHolder(ViewGroup parent, int viewType) the signature already suggest different view types. For each one of them you'll require a different viewholder too, and subsequently each one of them can have a different set of clicks. Or you can just create a generic viewholder that takes any view and one onClickListener and applies accordingly. Or delegate up one level to the orchestrator so several fragments/activities have the same list with different click behaviour. Again, all flexibility is on your side.

这是一个真正需要的成分，相当接近了我们的内部实现和改进的ListView 是到现在为止。这是很好的，谷歌终于承认了。

It is a really needed component and fairly close to what our internal implementations and improvements to ListView were until now. It's good that Google finally acknowledges it.

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