如何修复将 JSON 数据添加到 ArrayList 并更新到 ArrayAdapter

Question

这段代码只是查询Google本书API和returnJSON中的数据。然后，解析 JSON 数据并将书名、作者和出版日期存储在类型 'Book' 的 ArrayList 中。尝试解析 JSON 数据数组时出现问题。它不会从 MainActivity.java class 中的第 70 行的循环中出来。可能的解决方案是什么？

存储库是 https://github.com/PRAVEENT26/GoogleBooksAPI

我也会在这里列出文件。

MainActivity.java

package com.praveent.googlebooksapi;
import android.net.Uri;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;

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

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.Scanner;
import static java.lang.System.in;

public class MainActivity extends AppCompatActivity {

  EditText query;
  Button submit;
  String dataJSON;
  TextView test;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    query = (EditText) findViewById(R.id.query);
    submit = (Button) findViewById(R.id.submit);
    final String baseURL = "https://www.googleapis.com/books/v1/volumes";
    final String queryParameter = "q";

    submit.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
        String searchQuery = query.getText().toString();

        Uri tempUri = Uri.parse(baseURL).buildUpon().appendQueryParameter(queryParameter, searchQuery).build();
        URL url;
        try {
          url = new URL(tempUri.toString());
          new fetchDataAsync().execute(url);
        } catch (IOException e) {
          e.printStackTrace();
        }


      }
    });
  }

  public void jsonParsing() throws JSONException {
    JSONObject response = new JSONObject(dataJSON);
    int total = response.getInt("totalItems");
    TextView test = (TextView) findViewById(R.id.test);
    int flag = 0;
    JSONArray bookArray = response.getJSONArray("items");
    //test.setText(Integer.toString(bookArray.length()));
    ArrayList < Book > bookList = new ArrayList < > ();
    ListView listView = (ListView) findViewById(R.id.commonView);
    for (int i = 0; i < total; i++) {

      flag++;
      JSONObject volume = bookArray.getJSONObject(i);
      if (volume.has("volumeInfo")) {
        JSONObject tempObject = volume.getJSONObject("volumeInfo");
        String bookName = tempObject.getString("title");
        String authorName = null;
        if (tempObject.has("authors")) {
          JSONArray authorsArray = tempObject.getJSONArray("authors");
          for (int j = 0; j < authorsArray.length(); j++) {
            authorName += authorsArray.getString(j);
            if (j < authorsArray.length() - 1) {
              authorName += ", ";
            }
          }
        }
        String publicationDate = tempObject.getString("publishedDate");
        bookList.add(new Book(bookName, authorName, publicationDate));
      }
    }
    test.setText(Integer.toString(flag));
    BookAdapter bookAdapter = new BookAdapter(this, bookList);
    listView.setAdapter(bookAdapter);
  }

  public class fetchDataAsync extends AsyncTask < URL, Void, String > {

    @Override
    protected String doInBackground(URL...url) {
      URL searchURL = url[0];
      try {
        dataJSON = fetchData(searchURL);

      } catch (IOException e) {
        e.printStackTrace();
      }
      return dataJSON;
    }

    @Override
    protected void onPostExecute(String s) {
      try {
        jsonParsing();
      } catch (JSONException e) {
        e.printStackTrace();
      }
    }
  }

  public static String fetchData(URL url) throws IOException {
    HttpURLConnection newConnection = (HttpURLConnection) url.openConnection();
    try {
      InputStream newStream = newConnection.getInputStream();
      Scanner scanner = new Scanner(newStream);
      scanner.useDelimiter("\A");
      boolean hasInput = scanner.hasNext();
      if (hasInput) {
        return scanner.next();
      } else
        return null;
    } finally {
      newConnection.disconnect();
    }
  }
}

BookAdapter.java

package com.praveent.googlebooksapi;

    import android.app.Activity;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ArrayAdapter;
    import android.widget.ImageView;
    import android.widget.TextView;

    import java.util.ArrayList;

    public class BookAdapter extends ArrayAdapter<Book>{

    public BookAdapter(Activity context, ArrayList<Book> bookArrayListAdapter) {
        super(context, 0, bookArrayListAdapter);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View tempView = convertView;
        if (tempView == null){
            tempView = LayoutInflater.from(getContext()).inflate(R.layout.book_details,parent,false);
        }
        Book temp = getItem(position);
        ImageView imageView = (ImageView) tempView.findViewById(R.id.image);
        TextView nameView = (TextView) tempView.findViewById(R.id.bookName);
        TextView authorView = (TextView) tempView.findViewById(R.id.authorName);
        TextView dateView = (TextView) tempView.findViewById(R.id.publishDate);

        imageView.setImageResource(R.drawable.google);
        nameView.setText(temp.getbookName());
        authorView.setText(temp.getAuthorName());
        dateView.setText(temp.getPublishedDate());

        return tempView;
    }
    }

Book.java //自定义对象

package com.praveent.googlebooksapi;

    public class Book {


    String bookName;
    String authorName;
    String publishedDate;
    public Book(String name, String authors, String date){
        bookName = name;
        authorName = authors;
        publishedDate = date;
    }

    public String getbookName() {
        return bookName;
    }
    public String getAuthorName() {
        return authorName;
    }
    public String getPublishedDate() {
        return publishedDate;
    }

    }

XML 布局：

book_details.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="8dp">
    <ImageView
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:padding="8dp"
        android:id="@+id/image"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:padding="8dp">
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/bookName"
            android:textSize="16dp" />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/authorName"
            android:textSize="16dp" />
        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:id="@+id/publishDate"
            android:textSize="16dp" />
    </LinearLayout>

</LinearLayout>

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.praveent.googlebooksapi.MainActivity">

    <EditText
        android:id="@+id/query"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginTop="8dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="textPersonName"
        android:hint="Enter the Book Query" />


    <Button
        android:id="@+id/submit"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="SUBMIT QUERY" />
    <TextView
        android:id="@+id/test"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:layout_marginTop="8dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>
    <ListView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/commonView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:padding="16dp"/>

</LinearLayout>

ANDROID 清单文件：

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.praveent.googlebooksapi">
    <uses-permission android:name="android.permission.INTERNET"></uses-permission>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

样本JSON数据：Query Results in JSON。单击此处可查看 JSON 结构。

请帮助我运行没有任何问题。提前致谢！

Answer 1

试试这个，

try 
{
    JSONObject result = new JSONObject(resultResponse);
    String kind = result.getString("kind");

    JSONArray items_arr=result.getJSONArray("items");
    for(int i=0;i<items_arr.length();i++)
    {
        JSONObject obj=items_arr.getJSONObject(i);
        JSONObject volumeInfo_obj=obj.getJSONObject("volumeInfo");
        String bookName=volumeInfo_obj.getString("title");
        JSONArray volumeInfo_arr=volumeInfo_obj.getJSONArray("authors");
        String authorName=volumeInfo_arr.getString(0);

        String publicationDate=volumeInfo_obj.getString("publishedDate");

        bookList.add(new Book(bookName, authorName, publicationDate));
    }
    BookAdapter bookAdapter = new BookAdapter(this, bookList);
    listView.setAdapter(bookAdapter);

} catch (JSONException e) {
    Constants.dismiss_progress_dialog();
    e.printStackTrace();
}

如何修复将 JSON 数据添加到 ArrayList 并更新到 ArrayAdapter

How to fix adding JSON data to the ArrayList and updating to the ArrayAdapter

java

android

json

arraylist

google-books