Question

制作RecyclerView Adapter class并且不知道为什么getItem()方法丢失。

我的适配器类：

package com.example.pc.example;

import android.content.Context;
import android.database.Cursor;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class MyRecyclerAdapter extends RecyclerView.Adapter<MyRecyclerAdapter .MyHolder> {
    private Context mContext;
    private Cursor mCursor;

    public MyRecyclerAdapter (Cursor mCursor) {
        this.mCursor = mCursor;
    }


    @NonNull
    @Override
    public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        mContext = parent.getContext();
        View itemView = LayoutInflater.from(mContext).inflate(R.layout.row, parent, false);

        return new MyHolder(itemView);
    }

    @Override
    public void onBindViewHolder(@NonNull MyHolder holder, int position) {
        //here all my life i ussed the getItem() method, but now it is missing


    }

    @Override
    public int getItemCount() {
        return mCursor.getCount();
    }


    public class MyHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
        public TextView tv1, tv2;

        public MyHolder (View itemView) {
            super(itemView);
            tv1= (TextView) itemView.findViewById(R.id.tv1);
            tv2= (TextView) itemView.findViewById(R.id.tv2);
        }

        @Override
        public void onClick(View v) {

        }
    }
}

在ScreenShot中，您可以看到有getItemCount()，getItemId(position);和getItemViewType(position);，但没有getItem(position)。

CLICK FOR SCREENSHOT

有人可以解释我发生了什么吗？非常感谢提前！

Answer 1

缺少这个：

  public Model getItem(int position) {
    if (position < 0 || position >= getItemCount()) {
        throw new IllegalArgumentException("Item position is out of adapter's range");
    } else if (mCursor.moveToPosition(position)) {
        return new Model (mCursor);
    }
    return null;
}

Answer 2

扩展BaseAdapter并且通常与Adapter一起使用的

ListView有一个名为getItem(int position)的抽象方法，应该在具体的Adapter类中实现。

abstract getItem(int position)

RecyclerView.Adapter没有abstract getItem(int)方法。所以，你不能覆盖它......

RecyclerView.Adapter class.. There's no getItem(int) method

如果您需要在特定位置检索项目，您可以自己创建方法。只需添加您在其他答案中提到的代码：

public class MyRecyclerAdapter extends RecyclerView.Adapter<MyRecyclerAdapter .MyHolder> {

      public Model getItem(int position) {
        if (position < 0 || position >= getItemCount()) {
            throw new IllegalArgumentException("Item position is out of adapter's range");
        } else if (mCursor.moveToPosition(position)) {
            return new Model (mCursor);
        }
        return null;
    }
}

哪里有getItem（）方法？

2 个答案: