将已解析的JSONArray加载到recyclerView中

我正在尝试将API调用的结果加载到recyclerView中。我创建了一个数据模型来保存结果数组(字符串),以用于填充recyclerView Adapter。但是,一旦解析了JSON文件,应用程序就会在调用数据模型的“ setValues”时崩溃,但结果会准确地显示在logcat上。     我的代码如下:

主要活动

package com.limitless.googlebooks;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.loader.app.LoaderManager;
import androidx.loader.content.Loader;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.net.NetworkInterface;
import java.util.ArrayList;

import static android.text.TextUtils.isEmpty;

public class MainActivity extends AppCompatActivity
        implements LoaderManager.LoaderCallbacks<String> {
    private EditText bookImput;
    private RecyclerView recyclerView;
    private ProgressBar progressBar;
    private static Books books;
    ArrayList<Books> booksArray;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        bookImput = findViewById(R.id.bookInput);
        progressBar = findViewById(R.id.progressBar);
        recyclerView = findViewById(R.id.bookRecyclerView);
        booksArray =  new ArrayList<>();
        BooksAdapter adapter = new BooksAdapter(booksArray);
        recyclerView.setAdapter(adapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));

        if(LoaderManager.getInstance(this).getLoader(0) != null){
            LoaderManager.getInstance(this).initLoader(0,null, this);
        }
    }

    public void searchBooks(View view) {
        String queryText = bookImput.getText().toString();
        InputMethodManager methodManager = (InputMethodManager)
                getSystemService(Context.INPUT_METHOD_SERVICE);
        if(methodManager != null){
            methodManager.hideSoftInputFromWindow(view.getWindowToken(),
                    methodManager.HIDE_NOT_ALWAYS);
        }
        ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = null;
        if(connectivityManager != null){
            networkInfo = connectivityManager.getActiveNetworkInfo();
        }
        if(networkInfo != null && !isEmpty(queryText) && networkInfo.isConnected()){
            Bundle queryBundle = new Bundle();
            queryBundle.putString("queryString", queryText);
            LoaderManager.getInstance(this).restartLoader(0, queryBundle, this);
            progressBar.setVisibility(View.VISIBLE);
        }else {
            if(isEmpty(queryText)){
                Toast.makeText(this, R.string.emptyquery, Toast.LENGTH_SHORT).show();
            }else{
                Toast.makeText(this, R.string.no_internet, Toast.LENGTH_SHORT).show();
            }
        }
    }

    @NonNull
    @Override
    public Loader<String> onCreateLoader(int id, @Nullable Bundle args) {
        String queryString = "";
        if(args != null){
            queryString = args.getString("queryString");
        }
        return new BookLoader(this, queryString);
    }

    @Override
    public void onLoadFinished(@NonNull Loader<String> loader, String data) {
        try{
            JSONObject jsonObject = new JSONObject(data);
            JSONArray itemsArray = jsonObject.getJSONArray("items");

            int i = 0;
            String title = null;
            String authors = null;
            String publisher = null;
            String date = null;

            while(i < itemsArray.length() && title == null && authors == null && date == null){
                JSONObject book = itemsArray.getJSONObject(i);
                JSONObject volumeInfo = book.getJSONObject("volumeInfo");
                try{
                    title = volumeInfo.getString("title");
                    authors = volumeInfo.getString("authors");
                    publisher = volumeInfo.getString("publisher");
                    date = volumeInfo.getString("publishedDate");
                } catch (JSONException e) {
                    e.printStackTrace();
                }
                i++;
            }
            if(title != null && authors != null && date != null){
                books.setBookName(title);
                books.setAuthorsName(authors);
                books.setPublisher(publisher);
                books.setPublishedDate(date);
                booksArray.add(books);
            }else {
                books.setBookName(String.valueOf(R.string.no_results));
                books.setAuthorsName("");
                books.setPublisher("");
                books.setPublishedDate("");;
            }
        }catch (JSONException e){
            books.setBookName(String.valueOf(R.string.error));
            books.setAuthorsName("");
            books.setPublisher("");
            books.setPublishedDate("");
            e.printStackTrace();

        }
    }

    @Override
    public void onLoaderReset(@NonNull Loader<String> loader) {

    }
}

资料模型

package com.limitless.googlebooks;

public class Books {
    private String bookName;
    private String authorsName;
    private String publisher;
    private String publishedDate;

    public Books(String bookName, String authorsName, String publisher, String publishedDate) {
        this.bookName = bookName;
        this.authorsName = authorsName;
        this.publisher = publisher;
        this.publishedDate = publishedDate;
    }
    public Books(){}


    public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

    public String getAuthorsName() {
        return authorsName;
    }

    public void setAuthorsName(String authorsName) {
        this.authorsName = authorsName;
    }

    public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }

    public String getPublishedDate() {
        return publishedDate;
    }

    public void setPublishedDate(String publishedDate) {
        this.publishedDate = publishedDate;
    }
}

转接器类别

package com.limitless.googlebooks;

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

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;

public class BooksAdapter extends RecyclerView.Adapter<BooksAdapter.BooksHolder>{
    ArrayList<Books> booksArrayList;
    public BooksAdapter(ArrayList<Books> booksArray){
        this.booksArrayList = booksArray;
        }

    @NonNull
    @Override
    public BooksHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        Context context = parent.getContext();
        View itemView = LayoutInflater.from(context).inflate(R.layout.booklist, parent, false);
        return new BooksHolder(itemView);
    }

    @Override
    public void onBindViewHolder(@NonNull BooksHolder holder, int position) {
        Books books = booksArrayList.get(position);
        holder.bind(books);
    }

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

    public class BooksHolder extends RecyclerView.ViewHolder {
        private TextView bookName;
        private TextView authorsName;
        private TextView publisher;
        private TextView publishedDate;

        public BooksHolder(@NonNull View itemView) {
            super(itemView);

            bookName = itemView.findViewById(R.id.bookTitle);
            authorsName = itemView.findViewById(R.id.authorsName);
            publisher = itemView.findViewById(R.id.publisher);
            publishedDate = itemView.findViewById(R.id.publishedDate);
        }

        public void bind(Books books){
            bookName.setText(books.getBookName());
            authorsName.setText(books.getAuthorsName());
            publisher.setText(books.getPublisher());
            publishedDate.setText(books.getPublishedDate());
        }
    }

}
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