AsyncTaskLoaderを使用してJSONのrecyclerviewでデータを表示

Question

私はJSONからのデータをrecyclerviewに投稿しようとしています。 AsyncTaskLoaderを使用していますが、画面上に何も表示されません。 JSONから必要なデータをログに記録して、解析の権利があることを確認し、表示されます。私はまた、表示されることを意図されたオブジェクトの配列を記録しており、それらはlogcatにも表示されます。これは、私のアプリケーションの画面で、データを表示しません。私は2つのフラグメントを持つビューページャを使用していますが、この問題は両方で同じです。問題は同じ

public class TechNewsFragment extends Fragment { 
private SwipeRefreshLayout mSwipeRefreshLayout; 
private TextView mErrorMessage; 
private NewsAdapter mNewsAdapter; 
ArrayList<News> news; 
NetworkInfo info; 
// The Loader takes in a bundle 
Bundle sourceBundle = new Bundle(); 

private final String LOG_TAG = MainActivity.class.getSimpleName(); 

private static final String TECH_NEWS_QUERY_URL = "query"; 
private static final String TECH_NEWS_SOURCE = "techcrunch"; 
private static final int TECH_NEWS_LOADER = 22; 

private RecyclerView mRecyclerView; 


public TechNewsFragment() { 
    // Required empty public constructor 
} 

@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 
    View view = inflater.inflate(R.layout.fragment_news, container, false); 
    mErrorMessage = (TextView) view.findViewById(R.id.tv_error_message); 
    mRecyclerView = (RecyclerView) view.findViewById(R.id.recycler_view_main); 
    mSwipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.swipeRefresh); 

    mRecyclerView.setLayoutManager(new LinearLayoutManager(getContext(), LinearLayoutManager.VERTICAL, false)); 


    getActivity().getSupportLoaderManager().initLoader(TECH_NEWS_LOADER, null, new NewsDataLoader()); 

    mSwipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { 
     @Override 
     public void onRefresh() { 
      Log.v(LOG_TAG, "Refreshing"); 
      restartLoader(); 
      mSwipeRefreshLayout.setColorSchemeResources(
        R.color.colorPrimary, 
        R.color.colorPrimaryDark); 
     } 
    }); 

    return view; 
} 

private boolean isConnected(){ 
    ConnectivityManager cm = (ConnectivityManager) getActivity() 
      .getSystemService(CONNECTIVITY_SERVICE); 

    info = cm.getActiveNetworkInfo(); 

    return info != null && info.isConnectedOrConnecting(); 
} 

private int anyRandomInt(Random random) { 
    return random.nextInt(); 
} 

private void restartLoader() { 
    new Handler().postDelayed(new Runnable() { 
     @Override 
     public void run() { 
      URL techNewsUrl = TechNetworkUtils.buildUrl(TECH_NEWS_SOURCE); 
      sourceBundle.putString(TECH_NEWS_QUERY_URL, techNewsUrl.toString()); 

      Random random = new Random(); 
      int uniqueId = anyRandomInt(random); //Generates a new ID for each loader call; 

//     sourceBundle.putString("query", s);] 

      LoaderManager loaderManager = getActivity().getSupportLoaderManager(); 

      if (loaderManager.getLoader(TECH_NEWS_LOADER) == null) { 
       loaderManager.initLoader(uniqueId, sourceBundle, new NewsDataLoader()); 
      } else { 
       loaderManager.restartLoader(TECH_NEWS_LOADER, sourceBundle, new 
         NewsDataLoader()); 
      } 
     } 
    }, 5000); 
    mSwipeRefreshLayout.setRefreshing(false); 
    Log.v(LOG_TAG, "Finished refreshing"); 
} 

private void showErrorScreen(){ 
    mErrorMessage.setVisibility(View.VISIBLE); 
    mRecyclerView.setVisibility(View.INVISIBLE); 
    mErrorMessage.setText(getString(R.string.internet_error)); 
} 

`public class NewsDataLoader implements LoaderManager.LoaderCallbacks<ArrayList<News>> { 
    @Override 
    public Loader<ArrayList<News>> onCreateLoader(int id, final Bundle args) { 
     if (isConnected()){ 
      mErrorMessage.setVisibility(View.INVISIBLE); 
      mRecyclerView.setVisibility(View.VISIBLE); 
      return new AsyncTaskLoader<ArrayList<News>>(getActivity()) { 
       ArrayList<News> mNewsData; 

       @Override 
       protected void onStartLoading() { 
        super.onStartLoading(); 
        if (mNewsData != null){ 
         deliverResult(mNewsData); 
        }else{ 
         forceLoad(); 
         mSwipeRefreshLayout.setRefreshing(true); 
        } 
       } 

       @Override 
       public ArrayList<News> loadInBackground() { 
        try { 
         ArrayList<News> news = TechNetworkUtils.parseJSON(TECH_NEWS_SOURCE); 
         return news; 
        } catch (IOException e) { 
         e.printStackTrace(); 
         return null; 
        } 
       } 

       public void deliverResult(ArrayList<News> data) { 
        mNewsData = data; 
        super.deliverResult(data); 
       } 
      }; 
     }else{ 
      showErrorScreen(); 
      return null; 
     } 
    } 

    @Override 
    public void onLoadFinished(Loader<ArrayList<News>> loader, ArrayList<News> data) { 
     mSwipeRefreshLayout.setRefreshing(false); 
     if (null == data) { 
      showErrorScreen(); 
     } else { 
      mErrorMessage.setVisibility(View.INVISIBLE); 
      mRecyclerView.setVisibility(View.VISIBLE); 
      if (news != null) { 
//     news.clear(); 
       news.addAll(data); 
       mNewsAdapter = new NewsAdapter(news); 
       mRecyclerView.setAdapter(mNewsAdapter); 
       mNewsAdapter.notifyDataSetChanged(); 
      } else { 
       news = data; 
      } 
      Log.i(LOG_TAG + " this is the data", data.toString());   
// Array of objects shows in the log 
     } 
    } 

    @Override 
    public void onLoaderReset(Loader<ArrayList<News>> loader) { 
//   loader.forceLoad(); 
    } 

} 

}` 

あるので、 はここに私のFragmentActivityですが、私はこれは、ネットワーク接続に

public class TechNetworkUtils { 

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

public static ArrayList<News> parseJSON(String source) throws IOException { 
    URL url = buildUrl(source); 
    String jsonResult = getResponseFromHttpUrl(url); 

    ArrayList<News> news = new ArrayList<>(); 

    try{ 
     JSONObject jsonObject = new JSONObject(jsonResult); 
     JSONArray jsonArray = jsonObject.getJSONArray("articles"); 

     if (jsonArray != null){ 
      for (int i = 0; i < jsonArray.length(); i++){ 
       JSONObject article = jsonArray.getJSONObject(i); 
       String title = article.getString("title"); 
       String time = article.getString("publishedAt"); 
       news.add(new News(title, time)); 
       Log.i(LOG_TAG, title); 
       Log.i(LOG_TAG, time); 
      } 
     } 

    }catch (JSONException | NullPointerException e){ 
     e.printStackTrace(); 
     return null; 
    } 
    return news; 
} 

public static URL buildUrl(String techNewsSource){ 
    final String TECH_NEWS_BASE_URL = "https://newsapi.org/v1/articles"; 
    final String PARAM_SOURCE = "source"; 
    final String PARAM_SORT_BY = "sortBy"; 
    final String latest = "latest"; 
    final String PARAM_API_KEY = "apiKey"; 
    final String KEY = "3431d57e51a04c1d967e2eb96c99fd1a"; 

    Uri builtUri = Uri.parse(TECH_NEWS_BASE_URL).buildUpon() 
      .appendQueryParameter(PARAM_SOURCE, techNewsSource) 
      .appendQueryParameter(PARAM_SORT_BY, latest) 
      .appendQueryParameter(PARAM_API_KEY, KEY) 
      .build(); 

    Log.i(LOG_TAG, builtUri.toString()); 

    URL url = null; 
    try{ 
     url = new URL(builtUri.toString()); 
    }catch (MalformedURLException e){ 
     e.printStackTrace(); 
    } 
    return url; 
} 


public static String getResponseFromHttpUrl(URL url) throws IOException{ 
    HttpURLConnection urlConnection = null; 
    String newsJsonStr = null; 
    BufferedReader reader = null; 

    try{ 
     urlConnection = (HttpURLConnection) url.openConnection(); 
     urlConnection.setReadTimeout(15000); 
     urlConnection.setConnectTimeout(10000); 
     urlConnection.setRequestMethod("GET"); 
     urlConnection.setDoOutput(false); 
     urlConnection.setDoInput(true); 
     urlConnection.connect(); 

     InputStream inputStream = urlConnection.getInputStream(); 
     StringBuffer buffer = new StringBuffer(); 
     if(inputStream == null){ 
      return null; 
     } 

     reader = new BufferedReader(new InputStreamReader(inputStream)); 

     String line; 
     while ((line = reader.readLine()) != null){ 
      buffer.append(line + "\n"); 
     } 

     if (buffer.length() == 0){ 
      return null; 
     } 

     newsJsonStr = buffer.toString(); 

    }catch(IOException e){ 
     Log.e(LOG_TAG, "Error fetching data", e); 
     return null; 
    }finally{ 
     if (urlConnection != null){ 
      urlConnection.disconnect(); 
     } 
     if (reader != null){ 
      try{ 
       reader.close(); 
      }catch (IOException e){ 
       Log.e(LOG_TAG, "Error closing stream", e); 
      } 
     } 
    } 
    return newsJsonStr; 
} 
} 

をJSONを解析し、処理するためのクラスです。これは私のアダプタクラス

public class NewsAdapter extends 
RecyclerView.Adapter<NewsAdapter.NewsHolder> { 

// Variable used to reference the model 
private ArrayList<News> mNews = new ArrayList<>(); 

// NewsHolder class that extends the ViewHolder 
public static class NewsHolder extends RecyclerView.ViewHolder{ 
    private TextView mNewsTextView; 
    private TextView mTimeStampTextView; 

// Constructor to set the views 
    public NewsHolder(View itemView){ 
     super(itemView); 
     mNewsTextView = (TextView) itemView.findViewById(R.id.news_tv); 
     mTimeStampTextView = (TextView) itemView.findViewById(R.id.time_tv); 
    } 
} 

// Constructor to set the adapter 
public NewsAdapter(ArrayList<News> news){ 
    mNews = news; 
} 

@Override 
public NewsHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View view = 
LayoutInflater.from(parent.getContext()).inflate(R.layout.list_item_view, 
parent, false); 
    return new NewsHolder(view); 
} 

@Override 
public void onBindViewHolder(NewsHolder holder, int position) { 
    holder.mNewsTextView.setText(mNews.get(position).getNews()); 
    holder.mTimeStampTextView.setText(mNews.get(position).getTime()); 
} 

@Override 
public int getItemCount() { 
    return mNews.size(); 
} 
}` 

で一つだけを掲載します

これは私のpojoクラスです

public class News { 
private String mNews; 
private String mTime; 

public News(String news, String time){ 
    mNews = news; 
    mTime = time; 
} 

public String getNews() { 
    return mNews; 
} 

public String getTime() { 
    return mTime; 
} 
}` 

これは、これは私のlog.i

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06-06 21:35:25.834 1092-1092/com.ire.blogbot W/dalvikvm: VFY: unable to 
resolve instanceof 146 (Landroid/graphics/drawable/RippleDrawable;) in 
Landroid/support/v7/widget/AppCompatImageHelper; 
06-06 21:35:25.922 1092-1106/com.ire.blogbot I/MainActivity: 
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06-06 21:35:25.934 1092-1107/com.ire.blogbot I/MainActivity: 
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source=techcrunch&sortBy=latest&apiKey=3431d57e51a04c1d967e2eb96c99fd1a 
06-06 21:35:26.042 1092-1092/com.ire.blogbot W/EGL_genymotion: 
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06-06 21:35:26.270 376-449/system_process I/qtaguid: Failed write_ctrl(s 0 
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06-06 21:35:26.270 376-449/system_process W/NetworkManagementSocketTagger: 
setKernelCountSet(10021, 0) failed with errno -1 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: How can tech 
companies treat their contractors better? 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T21:19:28Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: Audi is the 
first to test autonomous vehicles in New York 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T20:58:34Z 
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Pro is a sophisticated and smart AirPods alternative 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T20:05:41Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: As the Surface 
line courts creatives, Apple pushes back with the iMac and iPad Pro 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T20:04:19Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: What Silicon 
Valley can learn from Lebanon’s women in tech 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T20:00:53Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: Matt Mitchell 
of CryptoHarlem is building an open source tool to help organizations 
prepare for data breaches 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T19:29:04Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: Pinterest 
raises $150M at a $12.3B valuation as it makes a full press into 
visual search 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T19:27:05Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: Tulip, the app 
platform for manufacturers, picks up $13 million from NEA 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T18:45:34Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: Take a look at 
these first pictures of Fisker’s $130K EMotion electric car 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T18:27:57Z 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: iOS 11 will 
help you free up storage on your iPhone through personalized suggestions 
06-06 21:35:27.182 1092-1107/com.ire.blogbot I/MainActivity: 2017-06- 
06T18:22:33Z 
06-06 21:35:27.182 1092-1092/com.ire.blogbot 
I/MainActivity  this is the data: [com.ire.blogbot.model.News@536e8250, 
com.ire.blogbot.model.News@536e65c0, com.ire.blogbot.model.News@536d157c, 
com.ire.blogbot.model.News@536e80ec, com.ire.blogbot.model.News@536e80f8, 
com.ire.blogbot.model.News@536e8104, com.ire.blogbot.model.News@536e8110, 
com.ire.blogbot.model.News@536e811c, com.ire.blogbot.model.News@536e8128, 
com.ire.blogbot.model.News@536e8134] 
06-06 21:35:27.202 1092-1106/com.ire.blogbot I/MainActivity: 
{"status":"ok","source":"entertainment-weekly","sortBy":"top","articles": 
[{"author":null,"title":"The Zodiac Killer: How a first-time filmmaker 
attempted to catch the serial 
murderer","description":null,"url":"http://zodiactruecrime.ew.com/","urlT 
oImage":null,"publishedAt":null},{"author":"Maureen Lee Lenker","title":"Sam 
Smith teases return to the recording studio with 
new photos","description":"","url":"http://ew.com/music/2017/06/06/sam- 
smith-teases-new- 
album/","urlToImage":"http://i0.wp.com/ewedit.files.wordpress.com/2017/06/g 
ettyimages-521740878.jpg? 
crop=0px%2C82px%2C2700px%2C1418px&resize=1200%2C630&ssl=1","publishedAt":"2 
017-06-06T21:22:08Z"},{"author":"Marisa Marcellino","title":"Highest- 
grossing 
Broadway shows of 
all time","description":"","url":"http://ew.com/theater/2017/06/06/highest- 
grossing-broadway-shows-of-all- 
time/","urlToImage":"http://i1.wp.com/ewedit.files.wordpress.com/2017/03/li 
onking.jpg? 
crop=0px%2C42px%2C2700px%2C1419px&resize=1200%2C630&ssl=1","publishedAt":"2 
017-06-06T19:52:02Z"},{"author":"Kyle Fowle","title":"'House of Cards' 
Recap: 
How Far Is Claire Willing to Go to Secure the 
Presidency?","description":"With threats forming all around them, Frank and 
Claire take violent action to secure their 
legacy","url":"http://ew.com/recap/house-of-cards-season-5-episode- 
12/","urlToImage":"http://i0.wp.com/ewedit.files.wordpress.com/2017/06/hoc_ 
512_unit_01846r.jpg? 
crop=3px%2C105px%2C2699px%2C1418px&resize=1200%2C630&ssl=1","publishedAt":" 
2017-06-06T19:49:12Z"},{"author":"Nivea Serrao","title":"Selena Gomez 
responds 
to ’13 Reasons Why’ controversy","description":"'This is happening every 
day'","url":"http://ew.com/tv/2017/06/06/selena-gomez-13-reasons-why- 
controversy- 
2/","urlToImage":"http://i1.wp.com/ewedit.files.wordpress.com/2017/04/13rw_ 
113_01153r.jpg? 
crop=0px%2C53px%2C2700px%2C1418px&resize=1200%2C630&ssl=1","publishedAt":"2 
017-06-06T19:45:59Z"},{"author":"Ruth Kinane","title":"‘Hollywood Game 
Night’ 
teaser: ‘This Is Us,’ ‘Veep,’ ‘Walking Dead’ casts ready 
for battle","description":"Jane Lynch returns to 
host","url":"http://ew.com/tv/2017/06/06/hollywood-game-night-teaser-this- 
is-us-veep-walking-dead- 
casts/","urlToImage":"http://i1.wp.com/ewedit.files.wordpress.com/2017/06/h 
ollywoodgame.jpg? 
crop=0px%2C21px%2C2700px%2C1419px&resize=1200%2C630&ssl=1","publishedAt":"2 
017-06-06T19:30:49Z"},{"author":"Joey Nolfi","title":"Watch Jerry Seinfeld 
refuse a hug from Kesha","description":"\"I don't know who that was... I 
wish her the best,\" the 63-year-old 
said","url":"http://ew.com/news/2017/06/06/jerry-seinfeld-kesha- 
hug/","urlToImage":"http://i0.wp.com/ewedit.files.wordpress.com/2017/06/sei 
nfeldkesha.jpg? 
crop=0px%2C13px%2C3200px%2C1681px&resize=1200%2C630&ssl=1","publishedAt":"2 
017-06-06T19:05:57Z"},{"author":"Maureen Lee Lenker","title":"Tonys 2017: 
Watch 
performances from this year’s Best 
Musical nominees","description":"","url":"http://ew.com/theater/2017/06/06/ 
tonys-2017-nominations-best-musical- 
performances/","urlToImage":"http://i2.wp.com/ewedit.files.wordpress.com/20 
17/0 
6/deh-ben-platt-4449-photo.jpg? 
crop=0px%2C382px%2C2700px%2C1419px&resize=1200%2C630&ssl=1","publishedAt":" 
2017 
-06-06T19:00:59Z"},{"author":"Ray Rahman","title":"‘Broad City’ returns 
under a ‘cloud of doom,’ stars tease","description":"Plus: RuPaul makes a 
'f---ing titillating' and 'godlike' 
cameo","url":"http://ew.com/tv/2017/06/06/broad-city-season-4- 
winter/","urlToImage":"http://i2.wp.com/ewedit.files.wordpress.com/2017/06/ 
broadcity.jpg? 
crop=0px%2C87px%2C2700px%2C1419px&resize=1200%2C630&ssl=1","publishedAt":"2 
017-06-06T18:56:12Z"},{"author":"Nivea Serrao","title":"How ‘The Moth’ 
podcast 
turned storytelling into a 
worldwide movement","description":"","url":"http://ew.com/podcasts/2017/06/ 
06/the-moth-podcast-20th- 
anniversary/","urlToImage":"http://i1.wp.com/ewedit.files.wordpress.com/201 
7/06/gettyimages-530299778.jpg? 
crop=0px%2C18px%2C1800px%2C945px&resize=1200%2C630","publishedAt":"2017- 
06-06T18:48:15Z"}]} 
06-06 21:35:33.406 376-386/system_process I/ActivityManager: No longer want 
com.android.exchange (pid 870): hidden #16 
06-06 21:41:36.890 55-55/? W/Genyd: Can't parse request 
06-06 21:41:36.958 376-466/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:36.958 376-466/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:36.958 376-389/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:36.958 376-389/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:36.958 376-389/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:37.158 376-466/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:37.158 376-466/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:37.162 376-389/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:37.162 376-389/system_process I/ClipboardService: Got clipboard 
for user=0 
06-06 21:41:37.162 376-389/system_process I/ClipboardService: Got clipboard 
for user=0 

である私のlist_item_layout

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


<FrameLayout 
android:layout_width="match_parent" 
android:layout_height="wrap_content" 
android:id="@+id/title_frame"> 

    <TextView 
     android:padding="16dp" 
     android:layout_width="match_parent" 
     android:layout_height="64dp" 
     android:id="@+id/news_tv" 
     tools:text="Get exciting news here"/> 

</FrameLayout> 
<FrameLayout 
android:layout_width="wrap_content" 
android:layout_height="wrap_content" 
android:layout_gravity="end"> 

    <TextView 
     android:id="@+id/time_tv" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:paddingBottom="8dp" 
     android:paddingRight="16dp" 
     tools:text="12:00pm"/> 
</FrameLayout> 

</LinearLayout> 

である私は、アプリを起動し、onSwipeRefreshLayoutが呼び出されたときにリフレッシュされたときにデータを自動的に表示する必要があります。

Answer 1

私はあなたのプロジェクトを実行していると私はあなたがlogcatから投稿したエラーではなく、私はこのコード行でNullPointerExceptionを持ってませんでした：

String techNewsUrlString = args.getString(TECH_NEWS_QUERY_URL);

だから私はとargsを置き換えますあなたのsourceBundleとそれがエラーを修正：

String techNewsUrlString = sourceBundle.getString(TECH_NEWS_QUERY_URL);

第二の問題は、あなたのfragment_news XMLコードにありました。

<?xml version="1.0" encoding="utf-8"?> 
<android.support.v4.widget.SwipeRefreshLayout 
xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:id="@+id/swipeRefresh" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:paddingBottom="@dimen/activity_vertical_margin" 
android:paddingLeft="@dimen/activity_horizontal_margin" 
android:paddingRight="@dimen/activity_horizontal_margin" 
android:paddingTop="@dimen/activity_vertical_margin"> 
<RelativeLayout 
android:layout_width="match_parent" 
android:layout_height="match_parent"> 
<TextView 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/tv_error_message" 
    android:text="Oops! Couldn't connect to a network" 
    android:gravity="center" 
    android:layout_margin="32dp" 
    android:textSize="16sp" 
    android:fontFamily="monospace" 
    android:visibility="invisible"/> 
<android.support.v7.widget.RecyclerView 
    android:id="@+id/recycler_view_main" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" /> 
</RelativeLayout> 
</android.support.v4.widget.SwipeRefreshLayout> 

そして、あなたのプロジェクトが動作するようになりました：あなたのTextViewすべてのスペースを占有してRecyclerviewの余地がありませんでしたので、私はいくつかの変更を行いました。