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Мне нужно, чтобы кто-нибудь сказал мне, каковы основные необходимые библиотеки для базового приложения, которое отображает список массивов в recyclerview. Я выполнил все шаги, и в Android studio нет ошибок, но приложение не показало «Строки» из массива, который я передал адаптеру, оно показывает только цифры от 1 до 20 без каких-либо букв. это основной файл активности

 package com.android.a0202;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.content.Context;
import android.os.Bundle;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;

import java.util.Scanner;
public class MainActivity extends AppCompatActivity {



    /*
     * References to RecyclerView and Adapter to reset the list to its
     * "pretty" state when the reset menu item is clicked.
     */
    private GreenAdapter mAdapter;
    private RecyclerView mNumbersList;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
          final String[]  NUM_LIST_ITEMS = new String[20];
        NUM_LIST_ITEMS[0]="8451";
        NUM_LIST_ITEMS[1]="85";
        NUM_LIST_ITEMS[2]="852";
        NUM_LIST_ITEMS[3]="526585";
        NUM_LIST_ITEMS[4]="84565";
        NUM_LIST_ITEMS[7]="rctvybun";
        NUM_LIST_ITEMS[8]="zxctvybunmi";
        NUM_LIST_ITEMS[9]="drtyuhi";
        NUM_LIST_ITEMS[10]="xerctvybunm";
        NUM_LIST_ITEMS[11]="ercvtyn";
        NUM_LIST_ITEMS[12]="lkxghj";
        NUM_LIST_ITEMS[13]="85";
        NUM_LIST_ITEMS[14]="534546";
        NUM_LIST_ITEMS[15]="454645";
        NUM_LIST_ITEMS[16]="xcvbnj";
        NUM_LIST_ITEMS[17]="cv";
        NUM_LIST_ITEMS[18]="cvb";
        NUM_LIST_ITEMS[19]="/";


        /*
         * Using findViewById, we get a reference to our RecyclerView from xml. This allows us to
         * do things like set the adapter of the RecyclerView and toggle the visibility.
         */
        mNumbersList = (RecyclerView) findViewById(R.id.rv_numbers);
        /*
         * A LinearLayoutManager is responsible for measuring and positioning item views within a
         * RecyclerView into a linear list. This means that it can produce either a horizontal or
         * vertical list depending on which parameter you pass in to the LinearLayoutManager
         * constructor. By default, if you don't specify an orientation, you get a vertical list.
         * In our case, we want a vertical list, so we don't need to pass in an orientation flag to
         * the LinearLayoutManager constructor.
         *
         * There are other LayoutManagers available to display your data in uniform grids,
         * staggered grids, and more! See the developer documentation for more details.
         */
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        mNumbersList.setLayoutManager(layoutManager);
        /*
         * Use this setting to improve performance if you know that changes in content do not
         * change the child layout size in the RecyclerView
         */
        mNumbersList.setHasFixedSize(true);
        /*
         * The GreenAdapter is responsible for displaying each item in the list.
         */
        mAdapter = new GreenAdapter(NUM_LIST_ITEMS);
        mNumbersList.setAdapter(mAdapter);
    }

}
 

и это файл адаптера

   package com.android.a0202;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.recyclerview.widget.RecyclerView;

public class GreenAdapter extends RecyclerView.Adapter<GreenAdapter.NumberViewHolder> {

//    final private ListItemClickListener monClicklistener;
    // TODO (1) Create a layout resource in res/layout/ called number_list_item.xml

    // Do steps 2 - 11 within number_list_item.xml
    // TODO (2) Make the root layout a FrameLayout
    // TODO (3) Make the width match_parent and the height wrap_content
    // TODO (4) Set the padding to 16dp
    // TODO (5) Add a TextView as the only child of the FrameLayout
    // TODO (6) Give the TextView an ID "@ id/tv_item_number"
    // TODO (7) Set the height and width to wrap_content
    // TODO (8) Align the TextView to the start of the parent
    // TODO (9) Center the TextView vertically in the layout
    // TODO (10) Set the font family to monospace
    // TODO (11) Set the text size to 42sp

    private static final String TAG = GreenAdapter.class.getSimpleName();
    private String[] mNumberItems;



 //   public interface ListItemClickListener {
   //     void onListItemClick(int clickedItemIndex);

    //}



    /**
     * Constructor for GreenAdapter that accepts a number of items to display and the specification
     * for the ListItemClickListener.
     *
     * @param numberOfItems Number of items to display in list
     */
    public GreenAdapter(String[] numberOfItems) {
        mNumberItems = numberOfItems;
    //    monClicklistener =listener;
    }

    /**
     *
     * This gets called when each new ViewHolder is created. This happens when the RecyclerView
     * is laid out. Enough ViewHolders will be created to fill the screen and allow for scrolling.
     *
     * @param viewGroup The ViewGroup that these ViewHolders are contained within.
     * @param viewType  If your RecyclerView has more than one type of item (which ours doesn't) you
     *                  can use this viewType integer to provide a different layout. See
     *
     *                  for more details.
     * @return A new NumberViewHolder that holds the View for each list item
     */
    @Override
    public NumberViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
        Context context = viewGroup.getContext();
        int layoutIdForListItem = R.layout.number_list_item;
        LayoutInflater inflater = LayoutInflater.from(context);
        boolean shouldAttachToParentImmediately = false;

        View view = inflater.inflate(layoutIdForListItem, viewGroup, shouldAttachToParentImmediately);
        NumberViewHolder viewHolder = new NumberViewHolder(view);

        return viewHolder;
    }

    /**
     * OnBindViewHolder is called by the RecyclerView to display the data at the specified
     * position. In this method, we update the contents of the ViewHolder to display the correct
     * indices in the list for this particular position, using the "position" argument that is conveniently
     * passed into us.
     *
     * @param holder   The ViewHolder which should be updated to represent the contents of the
     *                 item at the given position in the data set.
     * @param position The position of the item within the adapter's data set.
     */
    @Override
    public void onBindViewHolder(NumberViewHolder holder, int position) {
        Log.d(TAG, "#"   position);
        holder.bind(position);
    }

    /**
     * This method simply returns the number of items to display. It is used behind the scenes
     * to help layout our Views and for animations.
     *
     * @return The number of items available in our forecast
     */
    @Override
    public int getItemCount() {

        return 20;
    }

    public class NumberViewHolder extends RecyclerView.ViewHolder
   // implements View.OnClickListener
    {

       private TextView listItemNumberView ;
        public NumberViewHolder (View itemView){
            super(itemView);
           listItemNumberView = (TextView) itemView.findViewById(R.id.tv_item_number);
        }
        void bind (int listIndex){
            listItemNumberView.setText(String.valueOf(listIndex));
        }
      //  @Override
        //public void onClick(View view){
          //  int clickedPosition = getAdapterPosition();
           // monClicklistener.onListItemClick(clickedPosition);

        }


    }
    // TODO (12) Create a class called NumberViewHolder that extends RecyclerView.ViewHolder

    // TODO (13) Within NumberViewHolder, create a TextView variable called listItemNumberView

    // TODO (14) Create a constructor for NumberViewHolder that accepts a View called itemView as a parameter
    // TODO (15) Within the constructor, call super(itemView) and then find listItemNumberView by ID

    // TODO (16) Within the NumberViewHolder class, create a void method called bind that accepts an int parameter called listIndex
    // TODO (17) Within bind, set the text of listItemNumberView to the listIndex
    // TODO (18) Be careful to get the String representation of listIndex, as using setText with an int does something different
 

Вы должны изменить следующую строку.

 listItemNumberView.setText(String.valueOf(listIndex));
 

К следующему:

 listItemNumberView.setText(mNumberItems[listIndex]);
 

Вы не получили конкретный элемент из списка.

Попробуйте.