我正在探索RecyclerView,我很惊讶地看到,RecyclerView没有onItemClickListener()。

我有两个问题。

主要问题

我想知道为什么谷歌删除onItemClickListener()?

是否存在性能问题或其他问题?

次要的问题

我解决了我的问题写onClick在我的RecyclerView。适配器:

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) {

    }
}

这样可以吗/有更好的办法吗?


当前回答

RecyclerView没有一个onItemClickListener,因为RecyclerView负责回收视图(惊讶!),所以回收视图的责任是处理它接收到的点击事件。

这实际上使它更容易使用,特别是如果你有可以在多个地方点击的项目。


无论如何,检测点击一个RecyclerView项目是非常容易的。你所需要做的就是定义一个接口(如果你不使用Kotlin,在这种情况下你只需要传入一个lambda):

public class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {
    private final Clicks clicks;

    public MyAdapter(Clicks clicks) {
        this.clicks = clicks;
    }

    private List<MyObject> items = Collections.emptyList();

    public void updateData(List<MyObject> items) {
        this.items = items;
        notifyDataSetChanged(); // TODO: use ListAdapter for diffing instead if you need animations
    }

    public interface Clicks {
        void onItemSelected(MyObject myObject, int position);
    }

    public class MyViewHolder extends RecyclerView.ViewHolder {
        private MyObject myObject;    

        public MyViewHolder(View view) {
            super(view);
            // bind views
            view.setOnClickListener((v) -> {
                int adapterPosition = getBindingAdapterPosition();
                if(adapterPosition >= 0) {
                    clicks.onItemSelected(myObject, adapterPosition);
                }
            });
        }

        public void bind(MyObject myObject) {
            this.myObject = myObject;
            // bind data to views
        }
    }
}

Kotlin中的代码相同:

class MyAdapter(val itemClicks: (MyObject, Int) -> Unit): RecyclerView.Adapter<MyViewHolder>() {
    private var items: List<MyObject> = Collections.emptyList()

    fun updateData(items: List<MyObject>) {
        this.items = items
        notifyDataSetChanged() // TODO: use ListAdapter for diffing instead if you need animations
    }

    inner class MyViewHolder(val myView: View): RecyclerView.ViewHolder(myView) {
        private lateinit var myObject: MyObject

        init {
            // binds views
            myView.onClick {
                val adapterPosition = getBindingAdapterPosition()
                if(adapterPosition >= 0) {
                    itemClicks.invoke(myObject, adapterPosition)
                }
            }
        }

        fun bind(myObject: MyObject) {
            this.myObject = myObject
            // bind data to views
        }
    }
}

你不需要做的事情:

1)你不需要手动拦截触摸事件

2.)您不需要在子附加状态更改侦听器上添乱

3)你不需要RxJava中的PublishSubject/PublishRelay

只需使用点击侦听器。

其他回答

我用这个方法从RecyclerView开始一个Intent:

@Override
 public void onBindViewHolder(ViewHolder viewHolder, int i) {

    final MyClass myClass = mList.get(i);
    viewHolder.txtViewTitle.setText(myclass.name);
   ...
    viewHolder.itemView.setOnClickListener(new View.OnClickListener() {
      @Override
       public void onClick(View v){
             Intent detailIntent = new Intent(mContext, type.class);                                                            
             detailIntent.putExtra("MyClass", myclass);
             mContext.startActivity(detailIntent);
       }
}
);

我是这么做的,很简单:

只需为Clicked RecyclerView位置添加一行:

int position = getLayoutPosition()

ViewHolder类的完整代码:

private class ChildViewHolder extends RecyclerView.ViewHolder {
        public ImageView imageView;
        public TextView txtView;

        public ChildViewHolder(View itemView) {
            super(itemView);
            imageView= (ImageView)itemView.findViewById(R.id.imageView);
            txtView= (TextView) itemView.findViewById(R.id.txtView);
            itemView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Log.i("RecyclerView Item Click Position", String.valueOf(getLayoutPosition()));
                }
            });
        }
    }

希望这对你有所帮助。

检查这一个,我已经实现了所有的事情与适当的方式

RecyclerViewHolder类

public class RecyclerViewHolder extends RecyclerView.ViewHolder  {

    //view holder is for girdview as we used in the listView
    public ImageView imageView,imageView2;
    public RecyclerViewHolder(View itemView) {
        super(itemView);
        this.imageView=(ImageView)itemView.findViewById(R.id.image);
    }

}

适配器

public class RecyclerView_Adapter extends RecyclerView.Adapter<RecyclerViewHolder> {

    //RecyclerView will extend to recayclerview Adapter
    private ArrayList<ModelClass> arrayList;
    private Context context;
    private static RecyclerViewClickListener itemListener;
    //constructor of the RecyclerView Adapter
    RecyclerView_Adapter(Context context,ArrayList<ModelClass> arrayList,RecyclerViewClickListener itemListener){
        this.context=context;
        this.arrayList=arrayList;
        this.itemListener=itemListener;
    }

    @Override
    public RecyclerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        //this method will inflate the custom layout and return as viewHolder
        LayoutInflater layoutInflater=LayoutInflater.from(parent.getContext());
        ViewGroup mainGroup=(ViewGroup) layoutInflater.inflate(R.layout.single_item,parent,false);
        RecyclerViewHolder listHolder=new RecyclerViewHolder(mainGroup);

        return listHolder;
    }

    @Override
    public void onBindViewHolder(RecyclerViewHolder holder, final int position) {

        final ModelClass modelClass=arrayList.get(position);
        //holder
        RecyclerViewHolder mainHolder=(RecyclerViewHolder)holder;
        //convert the drawable image into bitmap
        Bitmap image= BitmapFactory.decodeResource(context.getResources(),modelClass.getImage());
        //set the image into imageView
        mainHolder.imageView.setImageBitmap(image);
        //to handle on click event when clicked on the recyclerview item and
        // get it through the RecyclerViewHolder class we have defined the views there
        mainHolder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //get the position of the image which is clicked
             itemListener.recyclerViewListClicked(v,position);
            }
        });

    }

    @Override
    public int getItemCount() {
        return (null!=arrayList?arrayList.size():0);
    }
}

的接口

public interface RecyclerViewClickListener {

    //this is method to handle the event when clicked on the image in Recyclerview
    public void recyclerViewListClicked(View v,int position);
}

//and to call this method in activity
RecyclerView_Adapter adapter=new RecyclerView_Adapter(Wallpaper.this,arrayList,this);
        recyclerView.setAdapter(adapter);
        adapter.notifyDataSetChanged();


    @Override
    public void  recyclerViewListClicked(View v,int position){

        imageView.setImageResource(wallpaperImages[position]);

    }

如果您有一个pojo列表,并且希望从适配器外部单击检索一个pojo,那么这里有一种非常容易实现它的方法。

在你的适配器中,为点击事件创建一个监听器和一个方法来设置它:

public class MyAdapter extends RecyclerView.Adapter<SitesListAdapter.ViewHolder> {
...
private List<MyPojo> mMyPojos;
private static OnItemClickListener mOnItemClickListener;

...
public interface OnItemClickListener {
    public void onItemClick(MyPojo pojo);
}

...
public void setOnItemClickListener(OnItemClickListener onItemClickListener){
    mOnItemClickListener = onItemClickListener;
}
...

}

在你的ViewHolder中,实现onClickListener并创建一个类成员来临时存储视图所呈现的POJO(这是一个例子,创建一个setter会更好):

public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
    public MyPojo mCurrentPojo;
    ...
    public ViewHolder(View view) {
        super(v);
        ...
        view.setOnClickListener(this); //You could set this on part of the layout too
    }

    ...
    @Override
    public void onClick(View view) {
        if(mOnItemClickListener != null && mCurrentPojo != null){
            mOnItemClickListener.onItemClick(mCurrentPojo);
        }
    }

回到你的适配器,当ViewHolder被绑定时设置当前POJO(如果当前视图没有,则设置为null):

@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
    final MyPojo currentPojo = mMyPojos.get(position); 
    holder.mCurrentPojo = currentPojo;
    ...

就是这样,现在你可以在你的fragment/activity中这样使用它:

    mMyAdapter.setOnItemClickListener(new mMyAdapter.OnItemClickListener() {
        @Override
        public void onItemClick(MyPojo pojo) {
            //Do whatever you want with your pojo here
        }
    });

使用RxJava和PublishSubject为点击公开一个Observable。

public class ReactiveAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    String[] mDataset = { "Data", "In", "Adapter" };

    private final PublishSubject<String> onClickSubject = PublishSubject.create();

    @Override 
    public void onBindViewHolder(final ViewHolder holder, int position) {
        final String element = mDataset[position];

        holder.itemView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
               onClickSubject.onNext(element);
            }
        });
    }

    public Observable<String> getPositionClicks(){
        return onClickSubject.asObservable();
    }
}

原来的帖子:

自从ListView的引入,onItemClickListener就一直存在问题。当你有一个内部元素的点击监听器时,回调不会被触发,但它没有被通知或良好的记录(如果有的话),所以有很多困惑和so问题。

考虑到RecyclerView更进一步,没有行/列的概念,而是任意布局的子节点数量,他们将onClick委托给每个子节点,或者委托给程序员实现。

不要认为Recyclerview是ListView的1:1替代品,而是一个更灵活的组件,用于复杂的用例。正如你所说,你的解决方案是谷歌对你的期望。现在您有了一个适配器,它可以将onClick委托给传递给构造函数的接口,这对于ListView和Recyclerview来说都是正确的模式。

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);
    }

}

然后在适配器上

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("VEGETABLES", "Poh-tah-tos"); };
           public void onTomato(ImageView callerImage) { Log.d("VEGETABLES", "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;
    } 
  ...

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.

它是一个非常需要的组件,非常接近我们的内部实现和到目前为止对ListView的改进。谷歌终于承认了这一点,这很好。