Recyclerview适配器与kotlin

在适配器中可以通过两种方式实现项目点击监听器。

第一种方法是使用界面

在你的活动课上:

class YourActivity : AppCompatActivity(), TestAdapter.ClickListener {
...
override fun itemClicked() {

}
...
}

在适配器类中:

class MyAdapter : RecyclerView.Adapter<MyAdapter.MyViewHolder> {
...
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
     holder.textView1.setOnClickListener { 
        clickListener.itemClicked(position) 
     }
}
...
interface ClickListener {
     fun itemClicked(position : Int)
}
...
}

第二种方法是使用callBack调用

在适配器类中:

class MyAdapter(val callBack: (pos:Int) -> Unit) : RecyclerView.Adapter<MyAdapter.MyViewHolder> {
...
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
     holder.textView1.setOnClickListener { 
        callBack(position)
     }
}
}

在你的活动课上:

class YourActivity : AppCompatActivity() {
...
val testAdapter = TestAdapter(
            callBack = { index ->
               
            })
binding.recyclerView.layoutManager = LinearLayoutManager(this)
binding.recyclerView.adapter = testAdapter
...
}

下面是我的代码片段:

v.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        int newPosition = MainActivity.mRecyclerView.getChildAdapterPosition(v);
        Intent cardViewIntent = new Intent(c, MainActivityCards.class);
        cardViewIntent.putExtra("Position", newPosition);
        c.startActivity(cardViewIntent);
    }
});

v是onCreateViewHolder的视图 c为背景信息

基于Jacob Tabak的回答(+1)，我能够添加onLongClick监听器:

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;

public class RecyclerItemClickListener implements RecyclerView.OnItemTouchListener {
    public interface OnItemClickListener {
        void onItemClick(View view, int position);

        void onItemLongClick(View view, int position);
    }

    private OnItemClickListener mListener;

    private GestureDetector mGestureDetector;

    public RecyclerItemClickListener(Context context, final RecyclerView recyclerView, OnItemClickListener listener) {
        mListener = listener;

        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onSingleTapUp(MotionEvent e) {
                return true;
            }

            @Override
            public void onLongPress(MotionEvent e) {
                View childView = recyclerView.findChildViewUnder(e.getX(), e.getY());

                if (childView != null && mListener != null) {
                    mListener.onItemLongClick(childView, recyclerView.getChildAdapterPosition(childView));
                }
            }
        });
    }

    @Override
    public boolean onInterceptTouchEvent(RecyclerView view, MotionEvent e) {
        View childView = view.findChildViewUnder(e.getX(), e.getY());

        if (childView != null && mListener != null && mGestureDetector.onTouchEvent(e)) {
            mListener.onItemClick(childView, view.getChildAdapterPosition(childView));
        }

        return false;
    }

    @Override
    public void onTouchEvent(RecyclerView view, MotionEvent motionEvent) {
    }

    @Override
    public void onRequestDisallowInterceptTouchEvent(boolean disallowIntercept) {
    }
}

然后你可以这样使用它:

recyclerView.addOnItemTouchListener(new RecyclerItemClickListener(getActivity(), recyclerView, new RecyclerItemClickListener.OnItemClickListener() {
    @Override
    public void onItemClick(View view, int position) {
        // ...
    }

    @Override
    public void onItemLongClick(View view, int position) {
        // ...
    }
}));

很简单，添加这个类:

public class OnItemClickListener implements View.OnClickListener {
    private int position;
    private OnItemClickCallback onItemClickCallback;

    public OnItemClickListener(int position, OnItemClickCallback onItemClickCallback) {
        this.position = position;
        this.onItemClickCallback = onItemClickCallback;
    }

    @Override
    public void onClick(View view) {
        onItemClickCallback.onItemClicked(view, position);
    }

    public interface OnItemClickCallback {
        void onItemClicked(View view, int position);
    }
}

获取一个'OnItemClickCallback'接口实例，并把它放在你的activity或fragment中:

private OnItemClickListener.OnItemClickCallback onItemClickCallback = new OnItemClickListener.OnItemClickCallback() {
    @Override
    public void onItemClicked(View view, int position) {
    }
};

然后，将这个回调传递给你的recyclerView:

recyclerView.setAdapter(new SimpleStringRecyclerViewAdapter(Arrays.asList("1", "2", "3"), onItemClickCallback));

最后，这将是你的适配器:

public class SimpleStringRecyclerViewAdapter extends RecyclerView.Adapter<SimpleStringRecyclerViewAdapter.ViewHolder> {
    private List<String> mValues;
    private OnItemClickListener.OnItemClickCallback onItemClickCallback;

    public SimpleStringRecyclerViewAdapter(List<String> items, OnItemClickListener.OnItemClickCallback onItemClickCallback) {
        mValues = items;
        this.onItemClickCallback = onItemClickCallback;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {
        public final TextView mTextView;

        public ViewHolder(View view) {
            super(view);
            mTextView = (TextView) view.findViewById(R.id.txt_title);
        }
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, final int position) {
        holder.mTextView.setText(mValues.get(position));
        holder.mTextView.setOnClickListener(new OnItemClickListener(position, onItemClickCallback));
    }

    @Override
    public int getItemCount() {
        return mValues.size();
    }
}

在Kotlin中也是如此

inner class MyViewHolder(v: View, myOnClickListener: MyOnClickListener) : RecyclerView.ViewHolder(v) {
    init {
        v.setOnClickListener { v -> myOnClickListener.onClick(v, adapterPosition) }
    }
}

override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): MyViewHolder {
    val view = LayoutInflater.from(viewGroup.context).inflate(R.layout.myview, viewGroup, false)
    return MyViewHolder(view, mOnClickListener)
}

inner class MyOnClickListener {
    fun onClick(view: View, position: Int) {
        val item = mList[position]
        Toast.makeText(view.context, item, Toast.LENGTH_LONG).show()
    }
}

我是这样做的，没有不必要的类、检测器等。适配器中的简单代码。特别是针对longClick的更好解决方案。

public class PasswordAdapter extends RecyclerView.Adapter<PasswordAdapter.ViewHolder> {
    private final ClickListener clickListener;

    public PasswordAdapter(ClickListener clickListener) {
         this.clickListener = clickListener;
    }

    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener, View.OnLongClickListener {
        TextView name;

        public ViewHolder(View itemView) {
            super(itemView);
            itemView.setOnClickListener(this);
            itemView.setOnLongClickListener(this);
            name = (TextView) itemView.findViewById(R.id.card_name);
        }

        @Override
        public void onClick(View v) {
            int position = getBindingAdapterPosition();
            if (position >= 0) {
                clickListener.onItemClick(position, v);
            }
        }

        @Override
        public boolean onLongClick(View v) {
            int position = getBindingAdapterPosition();
            if (position >= 0) { 
                clickListener.onItemLongClick(position, v);
                return true;
            }
            return false;
        }
    }

    public interface ClickListener {
        void onItemClick(int position, View v);
        void onItemLongClick(int position, View v);
    }
}

然后在片段或活动中，点击:

PasswordAdapter mAdapter = new PasswordAdapter(
    new PasswordAdapter.ClickListener() {
        @Override
        public void onItemClick(int position, View v) {
            Log.d(TAG, "onItemClick position: " + position);
        }

        @Override
        public void onItemLongClick(int position, View v) {
            Log.d(TAG, "onItemLongClick pos = " + position);
        }
    }
);