时间戳

首页 > 解决方案 > RecyclerView中的片段ClickListener错误

android - RecyclerView中的片段ClickListener错误

问题描述

我已将 RecyclerView 从 Activity 转换为 Fragment 所有工作，但是当我单击项目时出现此错误：

java.lang.NullPointerException: Attempt to invoke interface method 'void fragment.MyRecyclerViewAdapter$MyClickListener.onItemClick(int, android.view.View)' on a null object reference

这个错误在myClickListener.onItemClick(getAdapterPosition(), v);

public class MyRecyclerViewAdapter extends RecyclerView
        .Adapter<MyRecyclerViewAdapter
        .DataObjectHolder> {
    private static String LOG_TAG = "MyRecyclerViewAdapter";
    private ArrayList<DataObject> mDataset;
    private static MyClickListener myClickListener;

    public static class DataObjectHolder extends RecyclerView.ViewHolder
            implements View
            .OnClickListener {
        TextView label;
        TextView dateTime;

        public DataObjectHolder(View itemView) {
            super(itemView);
            label = (TextView) itemView.findViewById(R.id.textView);
            dateTime = (TextView) itemView.findViewById(R.id.textView2);
            Log.i(LOG_TAG, "Adding Listener");
            itemView.setOnClickListener(this);
        }

        @Override
        public void onClick(View v) {
            myClickListener.onItemClick(getAdapterPosition(), v); //ERROR HERE
        }
    }

    public void setOnItemClickListener(MyClickListener myClickListener) {
        this.myClickListener = myClickListener;
    }

    public MyRecyclerViewAdapter(ArrayList<DataObject> myDataset) {
        mDataset = myDataset;
    }

    @Override
    public DataObjectHolder onCreateViewHolder(ViewGroup parent,
                                               int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.card_view_row, parent, false);

        DataObjectHolder dataObjectHolder = new DataObjectHolder(view);
        return dataObjectHolder;
    }

    @Override
    public void onBindViewHolder(DataObjectHolder holder, int position) {
        holder.label.setText(mDataset.get(position).getmText1());
        holder.dateTime.setText(mDataset.get(position).getmText2());
    }

    public void addItem(DataObject dataObj, int index) {
        mDataset.add(index, dataObj);
        notifyItemInserted(index);
    }

    public void deleteItem(int index) {
        mDataset.remove(index);
        notifyItemRemoved(index);
    }

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

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

此代码在片段中：

mView = inflater.inflate(R.layout.fragment_two, container, false);
        mRecyclerView = (RecyclerView) mView.findViewById(R.id.my_recycler_view);
        mRecyclerView.setHasFixedSize(false);
        mLayoutManager = new LinearLayoutManager(getContext());
        mRecyclerView.setLayoutManager(mLayoutManager);
        mAdapter = new MyRecyclerViewAdapter(getDataSet());
        mRecyclerView.setAdapter(mAdapter);
        return mView;

标签： androidandroid-fragmentsandroid-recyclerview

解决方案

你没有打电话

public void setOnItemClickListener(MyClickListener myClickListener) {
        this.myClickListener = myClickListener;
    }

从任何地方。

从您的适配器或片段中调用此方法。或者，如果您现在不想要，只需添加空检查 

@Override
public void onClick(View v) {
  if (myClickListener!= null) {
     myClickListener.onItemClick(getAdapterPosition(), v); //ERROR HERE
  }
}

并将以下代码添加到 Fragment 类中。

   ((MyRecyclerViewAdapter) mAdapter).setOnItemClickListener(new MyRecyclerViewAdapter.MyClickListener() {
        @Override
        public void onItemClick(int position, View v) {
            // Implement your logic to do after clicking on any item.
        }
    });

推荐阅读