BookListing app for Joey

BookActivity.java

package com.example.android.booklistb;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

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

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.nio.charset.Charset;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    // Tag for Log Messages
    public static final String LOG_TAG = MainActivity.class.getSimpleName();
    // Tag for API URL
    private static final String GOOGLE_BOOKS_BASE_URL = "https://www.googleapis.com/books/v1/volumes?maxResults=3&q=";

    Button mSearchButton;
    EditText mSearchField;
    BooksAdapter adapter;
    ListView listView;
    ArrayList<Books> books;


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

        mSearchButton = (Button) findViewById(R.id.search_button);
        mSearchField = (EditText) findViewById(R.id.search_editText);

        books = new ArrayList<>();

        // Create the adapter to convert the array to views
        adapter = new BooksAdapter(this, books);

        // Attach the adapter to a ListView
        listView = (ListView) findViewById(R.id.listView);
        listView.setAdapter(adapter);

        mSearchButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                    BookAsyncTask task = new BookAsyncTask();
                    task.execute();
            }
        });

        if (savedInstanceState != null) {
            books = (ArrayList<Books>) savedInstanceState.getSerializable("myKey");
            adapter.clear();
            adapter.addAll(books);
            adapter.notifyDataSetChanged();
        }
    }

    @Override
    public void onSaveInstanceState(Bundle savedState) {
        super.onSaveInstanceState(savedState);
        savedState.putSerializable("myKey", books);

        //Toast.makeText(this, "onSaveInstanceState()", Toast.LENGTH_LONG).show();
        //Toast.makeText(this, "onSaveInstanceState() List Size: " + books.size(), Toast.LENGTH_SHORT).show();
    }

    /**
     * update the screen to display information from the given {@link Books}
     * @param booksList
     */
    private void updateUi(ArrayList<Books> booksList) {
        books.clear();
        books.addAll(booksList);

        adapter.clear();
        adapter.addAll(booksList);
        adapter.notifyDataSetChanged();
    }

    public static String firstWord(String input) {
        return input.split(" ")[0]; //Create array of words and return the 0th word
    }

    /**
     * {@link AsyncTask} to perform the network request on a background thread, and then
     * update the UI with the first earthquake in the response.
     */
    private class BookAsyncTask extends AsyncTask<URL, Void, ArrayList<Books>> {

        String userInput = mSearchField.getText().toString();
        String fw = null;

        @Override
        protected ArrayList<Books> doInBackground(URL... urls) {

            if (userInput.length() > 1) {
                fw = firstWord(userInput);
            } else
                if (userInput == null || userInput.equals("")) {
                   Log.e(LOG_TAG, "MainActivity " + "null if user inputs nothing");

                     //TOAST MSG seems to make it crash??
                     Toast.makeText(MainActivity.this, "Please enter search terms.", Toast.LENGTH_SHORT).show();

            return books;
            }

            URL url = createUrl(GOOGLE_BOOKS_BASE_URL + fw);
            Log.v("EditText", url.toString());

                //Perform HTTP request to the URL and receive a JSON response back
                String jsonResponse = "";
                try {
                    jsonResponse = makeHTTPRequest(url);
                } catch (IOException e) {
                    Log.e(LOG_TAG, "MainActivity " + "IOException", e);
                }


                //Extract relevant fields from the JSON response and create an {@link Event} object
                // books = extractFeatureFromJson(jsonResponse);

                // Return the {@link Books} object as the result of the {@link BookAsyncTask}

            return extractFeatureFromJson(jsonResponse);
            }


        /**
         * Update the screen with the given book (which was the result of the
         * {@link BookAsyncTask}
         */
        protected void onPostExecute(ArrayList<Books> booksList) {
            if (booksList == null) {
                return;
            }
            updateUi(booksList);
        }
    }

    /**
     * Returns new URL object from the given String URL.
     */
    private URL createUrl(String stringUrl) {

        URL url = null;

        try {
            url = new URL(stringUrl);
        } catch (MalformedURLException exception) {
            Log.e(LOG_TAG, "Error with creating URL", exception);
            return null;
        }
        return url;
    }




    /**
     * Make an HTTP request to the given URL and return a String as the response.
     */
    private String makeHTTPRequest(URL url) throws IOException {
        String jsonResponse = "";

        // if url is null, then return early
        if (url == null) {
            return jsonResponse;
        }

        HttpURLConnection urlConnection = null;
        InputStream inputStream = null;
        try {
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.setReadTimeout(10000 /* milliseconds */);
            urlConnection.setConnectTimeout(15000 /* milliseconds */);
            urlConnection.connect();
            // if the request was successful (response code 200);
            // then read the input stream and parse the response
            if (urlConnection.getResponseCode() == 200) {
                inputStream = urlConnection.getInputStream();
                jsonResponse = readFromStream(inputStream);

            } else {
                Log.e(LOG_TAG, "Error response code: " + urlConnection.getResponseCode());
            }
        } catch (IOException e) {
            Log.e(LOG_TAG, "Problem receiving book JSON results", e);
        } finally {
            if (urlConnection != null) {
                urlConnection.disconnect();
            }
            if (inputStream != null) {
                //function must handle java.io.IOException here
                inputStream.close();
            }
        }
        return jsonResponse;
    }

    /**
     * Convert the {@link InputStream} into a String which contains the
     * whole JSON response from the server.
     */
    private String readFromStream(InputStream inputStream) throws IOException {
        StringBuilder output = new StringBuilder();
        if (inputStream != null) {
            InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
            BufferedReader reader = new BufferedReader(inputStreamReader);
            String line = reader.readLine();
            while (line != null) {
                output.append(line);
                line = reader.readLine();
            }
        }
        return output.toString();
    }

    private ArrayList<Books> extractFeatureFromJson(String booksJSON) {

        // if JSON string is empty or null, return early
        if (TextUtils.isEmpty(booksJSON)) {
            return null;
        }

        ArrayList booksList = new ArrayList();

        try {
            JSONObject baseJsonResponse = new JSONObject(booksJSON);
            JSONArray itemsArray = baseJsonResponse.getJSONArray("items");

            // If there are results in the features array
            for (int i = 0; i< itemsArray.length(); i++) {
                //Extract out the first feature
                JSONObject firstFeature = itemsArray.getJSONObject(i);
                JSONObject items = firstFeature.getJSONObject("volumeInfo");

                //Extract out the title, time, and tsunami values
                String title = items.getString("title");
                String authors = "";
                JSONArray authorJsonArray = items.optJSONArray("authors");

                if (items.has("authors")) {
                    if (authorJsonArray.length() > 0) {
                        for (int j = 0; j < authorJsonArray.length(); j++){
                            authors = authorJsonArray.optString(j) + "";
                        }
                    }
                }

                //Create a new {@link Event} object, add the book to the array
                booksList.add(new Books(title, authors));
            }
            if (itemsArray.length() == 0) {
                Toast.makeText(MainActivity.this, "No results found.", Toast.LENGTH_SHORT).show();
                return null;
            }
        } catch (JSONException e) {
            Log.e(LOG_TAG, "Problem parsing the book JSON results", e);
        }
        return booksList;
    }
}