Change value in QueryUtils for each fragment

Question

How could I change the index value of a json object existing in my QueryUtils file from inside a Fragment?

This part right here: JSONObject currentDay = dayArray.getJSONObject(0);

I want the index value to change for each fragment but couldn't wrap my head around it. I have tried with intents and creating a constructor but failed.

As is right now, the app is 'working' with all fragments displaying the schedule for Monday (JSONObject index 0).

QueryUtils.java

import android.text.TextUtils;
import android.util.Log;

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;
import java.util.List;


public final class QueryUtils {

    private static final String LOG_TAG = QueryUtils.class.getSimpleName();

    //makeHttpRequest constants
    private static final int READ_TIMEOUT = 10000 /* milliseconds */;
    private static final int CONNECT_TIMEOUT = 15000 /* milliseconds */;
    private static final int RESPONSE_CODE = 200 /*everything is OK*/;

    public QueryUtils() {
    }

    public static List<Day> fetchDayData(String requestUrl) {

        URL url = createUrl(requestUrl);

        String jsonResponse = null;
        try {
            jsonResponse = makeHttpRequest(url);
        } catch (IOException e) {
            Log.e(LOG_TAG, "Problem making the HTTP request.", e);
        }

        List<Day> days = extractFeatureFromJson(jsonResponse);

        return days;
    }

    private static URL createUrl(String stringUrl) {
        URL url = null;
        try {
            url = new URL(stringUrl);
        } catch (MalformedURLException e) {
            Log.e(LOG_TAG, "Problem building the URL ", e);
        }
        return url;
    }
    private static String makeHttpRequest(URL url) throws IOException {
        String jsonResponse = "";

        if (url == null) {
            return jsonResponse;
        }

        HttpURLConnection urlConnection = null;
        InputStream inputStream = null;

        try {
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setReadTimeout(READ_TIMEOUT);
            urlConnection.setConnectTimeout(CONNECT_TIMEOUT);
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            if (urlConnection.getResponseCode() == RESPONSE_CODE) {
                inputStream = urlConnection.getInputStream();
                jsonResponse = readFromStream(inputStream);
            } else {
                Log.e(LOG_TAG, "Error response code: " + urlConnection.getResponseCode());
            }
        } catch (IOException e) {
            Log.e(LOG_TAG, "Problem retrieving Berceni JSON results.", e);
        } finally {
            if (urlConnection != null) {
                urlConnection.disconnect();
            }
            if (inputStream != null) {
                inputStream.close();
            }
        }
        return jsonResponse;
    }

    private static 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 static List<Day> extractFeatureFromJson(String dayJSON) {

        if (TextUtils.isEmpty(dayJSON)) {
            return null;
        }

        List<Day> days = new ArrayList<>();

        //Try to parse
        try {

            JSONObject baseJsonResponse = new JSONObject(dayJSON);

            JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");

            JSONObject currentDay = dayArray.getJSONObject(0);
            JSONArray getClasses = currentDay.getJSONArray("classes");

                for (int j = 0; j < getClasses.length(); j++) {
                    JSONObject currentClass = getClasses.getJSONObject(j);

                     String retrieveCourseTitle = currentClass.getString("class");
                     String retrieveCourseTime = currentClass.getString("time");
                     String retrieveCourseTrainer = currentClass.getString("trainer");
                     String retrieveCourseCancelState = currentClass.getString("canceled");

                     Day day = new Day(retrieveCourseTitle, retrieveCourseTime, retrieveCourseTrainer, retrieveCourseCancelState);
                     days.add(day);
                }

        } catch (JSONException e) {
            // If an error is thrown when executing any of the above statements in the "try" block,
            // catch the exception here, so the app doesn't crash. Print a log message
            // with the message from the exception.
            Log.e("QueryUtils", "Problem parsing JSON results", e);
        }

        return days;
    }

}

And my FragmentAdapter.java

import android.content.Context;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;

public class FragmentAdapter extends FragmentPagerAdapter {

    private Context mContext;

    public FragmentAdapter(Context context, FragmentManager fm) {
        super(fm);
        mContext = context;
    }

    @Override
    public Fragment getItem(int position) {
        if (position == 0) {
            return new MondayFragment();
        } else if (position == 1) {
            return new ThursdayFragment();
        } else if (position == 2) {
            return new WednesdayFragment();
        } else if (position == 3) {
            return new ThursdayFragment();
        } else if (position == 4) {
            return new FridayFragment();
        } else if (position == 5) {
            return new SaturdayFragment();
        } else {
            return new SundayFragment();
        }
    }

    /**
     * Return the total number of pages.
     */
    @Override
    public int getCount() {
        return 7;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        if (position == 0) {
            return mContext.getString(R.string.monday);
        } else if (position == 1) {
            return mContext.getString(R.string.tuesday);
        } else if (position == 2) {
            return mContext.getString(R.string.wednesday);
        } else if (position == 3) {
            return mContext.getString(R.string.thursday);
        } else if (position == 4) {
            return mContext.getString(R.string.friday);
        } else if (position == 5) {
            return mContext.getString(R.string.saturday);
        }   else {
            return mContext.getString(R.string.sunday);
        }
    }

}

JSON Sample Response

{  
   "schedule":{
      "day":[
         {  
            "id":"Monday",
            "classes":[
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                },
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }
            ]
         }, 
         {  
            "id":"Tuesday",
            "classes":[
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                },
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }
            ]
         }, 
         {  
            "id":"Wednesday",
            "classes":[
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }, 
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }
            ]
         },
         {  
            "id":"Thursday",
            "classes":[
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                },
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }
            ]
         }, 
         {  
            "id":"Friday",
            "classes":[
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                },
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }
            ]
         },
         {  
            "id":"Saturday",
            "classes":[
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }, 
                {
                    "class" : "Class",
                    "time" : "00:00",
                    "trainer" : "Teacher",
                    "canceled" : ""
                }
            ]
         }, 
         {  
            "id":"Sunday",
            "classes":[]
         }
      ]
   }
}

Answer 1

Looking at your POJO this isn't explicitly equal to your JSON.

A Day should be declared as:

class Day {
    String id;
    List<ClassDetail> classes;
}

class ClassDetail {
    //all the details
}

I think you are missconcepting your functions, the follow signature isn't too explicit.

List<Day> extractFeatureFromJson(String dayJSON)

In order to make it become more readable, I propose to change it for:
(You can use a Hashmap as recommended for @ρяσѕρєя):

HashMap<String, ClassDetail> parseScheduleJson(String scheduleJSON)

And the add each ClassDetail to the result

@Nullable
private static Map<String, List<ClassDetail>> parseScheduleJson(String scheduleJSON) {

    if (TextUtils.isEmpty(scheduleJSON)) {
        return null;
    }

    HashMap<String, List<ClassDetail>> result = new HashMap<>();

    try {
        JSONObject baseJsonResponse = new JSONObject(scheduleJSON);
        JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");

        for (int i = 0; i < dayArray.length(); i++) {
            ArrayList<ClassDetail> classes = new ArrayList<>();
            JSONObject currentDay = dayArray.getJSONObject(i);
            for (int j = 0; j < currentDay.getJSONArray("classes").length(); j++) {
                JSONObject currentClass = currentDay.getJSONArray("classes").getJSONObject(j);

                String retrieveCourseTitle = currentClass.getString("class");
                String retrieveCourseTime = currentClass.getString("time");
                String retrieveCourseTrainer = currentClass.getString("trainer");
                String retrieveCourseCancelState = currentClass.getString("canceled");

                classes.add(new ClassDetail(retrieveCourseTitle, retrieveCourseTime, retrieveCourseTrainer, retrieveCourseCancelState));
            }
            result.put(currentDay.getString("id"), classes);
        }

    } catch (JSONException e) {
        // If an error is thrown when executing any of the above statements in the "try" block,
        // catch the exception here, so the app doesn't crash. Print a log message
        // with the message from the exception.
        Log.e("QueryUtils", "Problem parsing JSON results", e);
        return null;
    }

    return result;
}

After this, you can access to your list of classes of the day using:

mymap.get("Monday");
mymap.get("Tuesday");
...
mymap.get("Sunday");

Edit:

IMHO, you have to call your dayloader in your activity, and inject the map result to your FragmentPagerAdapter:

public FragmentAdapter(Context context, FragmentManager fm, Map<String, List<ClassDetail> schedule) {
    super(fm);
    mContext = context;
    mSchedule = schedule;
}

@Override
public Fragment getItem(int position) {
    if (position == 0) {
        return MondayFragment.newInstance(mSchedule.get("Monday"));
    //...
    //same for all conditions
    //...
    } else {
        return SundayFragment.newInstance(mSchedule.get("Sunday"));
    }
}

After that when using newIntance pattern you can declare your fragments as:

private List<ClassDetail> mClasses;

public static MondayClassDetailFragment newInstance(ArrayList<ClassDetail> classes){
    MondayClassDetailFragment myFragment = new MondayClassDetailFragment();

    Bundle args = new Bundle();
    args.putParcelableArrayList("classes", classes);
    myFragment.setArguments(args);

    return myFragment;
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mClasses = getArguments().getParcelableArrayList("classes");
}

---

PS: Making http request and parsing a json manually at these days is a waste of energy. I recommend you to take a look to libraries to do this, in particulary to retrofit who is widely used and very well documented.

Answer 2

I'm not sure of this because I've never used FragmentPagerAdapter, but I suppose it works as any Adapter, conceptually.

What I am noticing in your code is that in your code (see comment)

private static List<Day> extractFeatureFromJson(String dayJSON) {

    if (TextUtils.isEmpty(dayJSON)) {
        return null;
    }

    List<Day> days = new ArrayList<>();

    //Try to parse
    try {

        JSONObject baseJsonResponse = new JSONObject(dayJSON);

        JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");

        JSONObject currentDay = dayArray.getJSONObject(0); //<<<<<<HERE
        JSONArray getClasses = currentDay.getJSONArray("classes");

            for (int j = 0; j < getClasses.length(); j++) {
                JSONObject currentClass = getClasses.getJSONObject(j);

                 String retrieveCourseTitle = currentClass.getString("class");
                 String retrieveCourseTime = currentClass.getString("time");
                 String retrieveCourseTrainer = currentClass.getString("trainer");
                 String retrieveCourseCancelState = currentClass.getString("canceled");

                 Day day = new Day(retrieveCourseTitle, retrieveCourseTime, retrieveCourseTrainer, retrieveCourseCancelState);
                 days.add(day);
            }

    } catch (JSONException e) {
        // If an error is thrown when executing any of the above statements in the "try" block,
        // catch the exception here, so the app doesn't crash. Print a log message
        // with the message from the exception.
        Log.e("QueryUtils", "Problem parsing JSON results", e);
    }

    return days;
}

You are doing the "extraction" only for JSONObject currentDay = dayArray.getJSONObject(0);

This means your List<Day> days will have only one Day in it, that is current day. Supposing you're feeding this List to your adapter, only a Day is found, hence nothing is changing.

I suggest you iterate through ALL the days, appending each day to the List with something like this:

try{
    JSONObject baseJsonResponse = new JSONObject(dayJSON);
    JSONArray dayArray = baseJsonResponse.getJSONObject("schedule").getJSONArray("day");
    for (int i = 0; i<dayArray.length();i++){
        JSONObject currentDay = dayArray.getJSONObject(i);
        //the rest
    }
}catch(JSONException e){
    //etc
}

Answer 3

While @crgarridos 's answer would work, I kept thinking of a faster and easier way of achieving my goal with minimum code modifications so:

I ended up modifying my JSON API and creating query url's for the id key so that I could query like this: URL?id=monday.

Next up I simply needed to add a URI builder and appendQueryParameter(key, value); for each of my fragments.