安卓下载器不工作

一个小时我不明白为什么工作室强调 return new ProfessionListLoader(MainActivity.this); 并且不允许应用程序运行。

import android.os.Bundle;
import android.support.v4.app.LoaderManager;
import android.support.v4.content.Loader;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import com.tanat.english_for_professions.R;
import com.tanat.english_for_professions.loader.ProfessionListLoader;
import java.util.ArrayList;
import butterknife.BindView;
import butterknife.ButterKnife;

public class MainActivity extends AppCompatActivity implements LoaderManager.LoaderCallbacks<ArrayList<String>> {
    private int LOADER_ID = 0;

    @BindView(R.id.professionList)
    ListView professionList;
    @BindView(R.id.toolbar)
    Toolbar toolbar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_activity);
        ButterKnife.bind(this);
        setSupportActionBar(toolbar);
        loadData();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

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

        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    @Override
    public Loader<ArrayList<String>> onCreateLoader(int id, Bundle args) {
        return new ProfessionListLoader(MainActivity.this);
    }

    @Override
    public void onLoadFinished(Loader<ArrayList<String>> loader, ArrayList<String> data) {

    }

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

    }

    private void loadData() {
        ArrayList data = null;
        if (data == null || data.size() == 0) {
            getSupportLoaderManager().initLoader(LOADER_ID, null, this);
        } else {
            createListAdapter(data);
        }
    }

    public void createListAdapter(ArrayList data) {
        ArrayAdapter<String> adapter;
        if (data != null) {
            adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, data);
            professionList.setAdapter(adapter);
        }
    }
}

装载机：

import android.content.AsyncTaskLoader;
import android.content.Context;
import android.util.Log;
import com.tanat.english_for_professions.R;
import com.tanat.english_for_professions.utils.JsonDisperse;
import org.json.JSONException;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;

public class ProfessionListLoader extends AsyncTaskLoader<ArrayList<String>> {
    private Context context;

    public ProfessionListLoader(Context context) {
        super(context);
        this.context = context;
    }

    String jsonString = "";
    InputStream inputStream;
    HttpURLConnection urlConnection = null;
    BufferedReader reader = null;

    @Override
    public ArrayList<String> loadInBackground() {
        try {
            URL url = new URL("url-url-url");

            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.setRequestMethod("GET");
            urlConnection.connect();

            inputStream = url.openConnection().getInputStream();
            StringBuffer buffer = new StringBuffer();
            reader = new BufferedReader(new InputStreamReader(inputStream));

            String line;
            while ((line = reader.readLine()) != null) {
                buffer.append(line);
            }
            jsonString = buffer.toString();
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        Log.d("loader", jsonString);
        JsonDisperse jsonDisperse = new JsonDisperse();
        jsonDisperse.saveStaticString(jsonString);

        try {
            return jsonDisperse.getListProfession(Integer.parseInt(context.getString(R.string.language)));
        } catch (JSONException e) {
            e.printStackTrace();
            return null;
        }
    }
}

如果你悬停，上下文会原谅，但我也给它。 请帮帮我。