My implementation of AsyncTaskLoader to avoid possible Memory Leak

ManActivity.java

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.example.android.sunshine;

import android.content.Context;
import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.AsyncTaskLoader;
import android.support.v4.content.Loader;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.example.android.sunshine.ForecastAdapter.ForecastAdapterOnClickHandler;
import com.example.android.sunshine.data.SunshinePreferences;
import com.example.android.sunshine.utilities.NetworkUtils;
import com.example.android.sunshine.utilities.OpenWeatherJsonUtils;

import java.lang.ref.WeakReference;
import java.net.URL;

public class MainActivity extends AppCompatActivity implements ForecastAdapterOnClickHandler,
        LoaderManager.LoaderCallbacks<String[]> {

    private static final String TAG = MainActivity.class.getSimpleName();

    private RecyclerView mRecyclerView;
    private ForecastAdapter mForecastAdapter;

    private TextView mErrorMessageDisplay;

    private ProgressBar mLoadingIndicator;

    private static final int WEATHER_LOADER_ID = 1;


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



        /*
         * 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.
         */
        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerview_forecast);

        /* This TextView is used to display errors and will be hidden if there are no errors */
        mErrorMessageDisplay = (TextView) findViewById(R.id.tv_error_message_display);

        /*
         * LinearLayoutManager can support HORIZONTAL or VERTICAL orientations. The reverse layout
         * parameter is useful mostly for HORIZONTAL layouts that should reverse for right to left
         * languages.
         */
        LinearLayoutManager layoutManager
                = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);

        mRecyclerView.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
         */
        mRecyclerView.setHasFixedSize(true);

        /*
         * The ForecastAdapter is responsible for linking our weather data with the Views that
         * will end up displaying our weather data.
         */
        mForecastAdapter = new ForecastAdapter(this);

        /* Setting the adapter attaches it to the RecyclerView in our layout. */
        mRecyclerView.setAdapter(mForecastAdapter);

        /*
         * The ProgressBar that will indicate to the user that we are loading data. It will be
         * hidden when no data is loading.
         *
         * Please note: This so called "ProgressBar" isn't a bar by default. It is more of a
         * circle. We didn't make the rules (or the names of Views), we just follow them.
         */
        mLoadingIndicator = (ProgressBar) findViewById(R.id.pb_loading_indicator);

        getSupportLoaderManager().initLoader(WEATHER_LOADER_ID, null, this);
    }


    /**
     * This method will get the user's preferred location for weather, and then tell some
     * background method to get the weather data in the background.
     */



    /**
     * This method is overridden by our MainActivity class in order to handle RecyclerView item
     * clicks.
     *
     * @param weatherForDay The weather for the day that was clicked
     */
    @Override
    public void onClick(String weatherForDay) {
        Context context = this;
        Class destinationClass = DetailActivity.class;
        Intent intentToStartDetailActivity = new Intent(context, destinationClass);
        intentToStartDetailActivity.putExtra(Intent.EXTRA_TEXT, weatherForDay);
        startActivity(intentToStartDetailActivity);
    }

    /**
     * This method will make the View for the weather data visible and
     * hide the error message.
     * <p>
     * Since it is okay to redundantly set the visibility of a View, we don't
     * need to check whether each view is currently visible or invisible.
     */
    private void showWeatherDataView() {
        /* First, make sure the error is invisible */
        mErrorMessageDisplay.setVisibility(View.INVISIBLE);
        /* Then, make sure the weather data is visible */
        mRecyclerView.setVisibility(View.VISIBLE);
    }

    /**
     * This method will make the error message visible and hide the weather
     * View.
     * <p>
     * Since it is okay to redundantly set the visibility of a View, we don't
     * need to check whether each view is currently visible or invisible.
     */
    private void showErrorMessage() {
        /* First, hide the currently visible data */
        mRecyclerView.setVisibility(View.INVISIBLE);
        /* Then, show the error */
        mErrorMessageDisplay.setVisibility(View.VISIBLE);
    }


    /**
     * This method uses the URI scheme for showing a location found on a
     * map. This super-handy intent is detailed in the "Common Intents"
     * page of Android's developer site:
     *
     * @see <a"http://developer.android.com/guide/components/intents-common.html#Maps">
     * <p>
     * Hint: Hold Command on Mac or Control on Windows and click that link
     * to automagically open the Common Intents page
     */
    private void openLocationInMap() {
        String addressString = "1600 Ampitheatre Parkway, CA";
        Uri geoLocation = Uri.parse("geo:0,0?q=" + addressString);

        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setData(geoLocation);

        if (intent.resolveActivity(getPackageManager()) != null) {
            startActivity(intent);
        } else {
            Log.d(TAG, "Couldn't call " + geoLocation.toString()
                    + ", no receiving apps installed!");
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        /* Use AppCompatActivity's method getMenuInflater to get a handle on the menu inflater */
        MenuInflater inflater = getMenuInflater();
        /* Use the inflater's inflate method to inflate our menu layout to this menu */
        inflater.inflate(R.menu.forecast, menu);
        /* Return true so that the menu is displayed in the Toolbar */
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        if (id == R.id.action_refresh) {
            invalidateData();
            getSupportLoaderManager().restartLoader(WEATHER_LOADER_ID, null, this);
            return true;
        }

        if (id == R.id.action_map) {
            openLocationInMap();
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    private void invalidateData() {
        mForecastAdapter.setWeatherData(null);
    }


    public static class WeatherLoader extends AsyncTaskLoader<String[]> {

        private String[] mWeatherData = null;
        private WeakReference<MainActivity> mActivity;
        private static final String TAG = WeatherLoader.class.getSimpleName();

        WeatherLoader(final MainActivity activity) {
            super(activity.getApplicationContext());
            mActivity = new WeakReference<>(activity);
        }

        private MainActivity getActivity() {
            return mActivity.get();
        }

        @Override
        protected void onStartLoading() {
            if (mWeatherData != null) {
                deliverResult(mWeatherData);
            } else {
                if (getActivity() != null)
                    getActivity().mLoadingIndicator.setVisibility(View.VISIBLE);
                else {
                    Log.e(TAG, "Failed to retrieve activity reference");
                    Toast.makeText(getContext(), "Loading . . .", Toast.LENGTH_LONG).show();
                }

                forceLoad();
            }
        }

        @Override
        public String[] loadInBackground() {
            String locationQuery = SunshinePreferences.getPreferredWeatherLocation(getContext());
            URL weatherRequestUrl = NetworkUtils.buildUrl(locationQuery);
            try {
                String jsonWeatherResponse = NetworkUtils.getResponseFromHttpUrl(weatherRequestUrl);
                return OpenWeatherJsonUtils.getSimpleWeatherStringsFromJson(
                        getContext(), jsonWeatherResponse
                );
            } catch (Exception e) {
                e.printStackTrace();
                return null;
            }

        }

        @Override
        public void deliverResult(String[] data) {
            mWeatherData = data;
            super.deliverResult(data);
        }
    }


    @Override
    public Loader<String[]> onCreateLoader(int id, final Bundle args) {
        return new WeatherLoader(this);
    }

    @Override
    public void onLoadFinished(Loader<String[]> loader, String[] data) {
        mLoadingIndicator.setVisibility(View.INVISIBLE);
        mForecastAdapter.setWeatherData(data);
        if (null != data) {
            showWeatherDataView();
        } else {
            showErrorMessage();
        }
    }

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

    }


}