Создал gridview в tablayout и попытался обновить Gridview с помощью службы Intent

Question

Я создал вкладку в закладке. Моя деятельность как следующий пункт для рассмотрения
1. Количество вкладок зависит от типа сортировки, доступного для объекта Source. Может быть максимум три вкладки, т. Е. Верхняя, последняя и популярная.
2. Каждая вкладка содержит GridView и должна обновляться, когда IntentService получает данные
3. Пользователь может выбрать источник из панели инструментов
4. Когда выбран новый источник, количество вкладок должно соответствовать новым источникам и GridView следует также обновить соответствующие

TabbedActivity

общественного класса TabbedActivity расширяет AppCompatActivity {

private Toolbar toolbar; 
private TabLayout tabLayout; 
private ViewPager mViewPager; 

private List<Source> allSourceItem; 

private Context context; 

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

    context = this; 

    // register broadcast 
    IntentFilter statusIntentFilter = new IntentFilter(Asset.ARTICLE_BROADCAST_ACTION); 
    TabbedActivity.ArticleStateReceiver mDownloadStateReceiver = new TabbedActivity.ArticleStateReceiver(); 
    LocalBroadcastManager.getInstance(this).registerReceiver(mDownloadStateReceiver, statusIntentFilter); 

    // set toolbar 
    toolbar = (Toolbar) findViewById(R.id.toolbar); 
    setSupportActionBar(toolbar); 

    // set tab layout 
    tabLayout = (TabLayout) findViewById(R.id.tab_layout); 

    // set the viewpager 
    mViewPager = (ViewPager) findViewById(R.id.container); 

    // set up page listner to viewpager 
    mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout)); 
    tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() { 
     @Override 
     public void onTabSelected(TabLayout.Tab tab) { 
      mViewPager.setCurrentItem(tab.getPosition()); 
     } 

     @Override 
     public void onTabUnselected(TabLayout.Tab tab) { 

     } 

     @Override 
     public void onTabReselected(TabLayout.Tab tab) { 

     } 
    }); 

    startSetUp(getRecentDisplayedData()); 

} 

public void startSetUp(Source src){ 

    int tabsCount = 3; 

    setTitle(src.getName()); 
    tabsCount = getNumberOfTabs(src.getSortByAvailableTop(),src.getSortByAvailableLatest(),src.getSortByAvailablePopular()); 

    setTabs(tabsCount); 
    tabLayout.setTabGravity(TabLayout.GRAVITY_FILL); 

    mViewPager.setAdapter(new SectionsPagerAdapter(getSupportFragmentManager(),tabsCount,src)); 

} 

// handle menus of activity 
@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    getMenuInflater().inflate(R.menu.menu_tabbed, menu); 
    return true; 
} 

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

    if (id == R.id.action_settings) { 
     Intent intent = new Intent(this, SourcesActivity.class); 
     intent.putExtra("SOURCE_ACTIVITY_ACTION","TABBED"); 
     startActivity(intent); 
     return true; 
    } 

    if(id == R.id.change_src){ 
     //get all selected sources 
     allSourceItem = Source.getAll(); 
     List<String> listItems = new ArrayList<String>(); 
     for(int i = 0; i < allSourceItem.size(); i++){ 
      listItems.add(allSourceItem.get(i).getName()); 
     } 

     final CharSequence[] items = listItems.toArray(new CharSequence[listItems.size()]); 

     AlertDialog.Builder builder = new AlertDialog.Builder(this); 
     builder.setTitle(R.string.chnage_news_source); 
     builder.setItems(items, new DialogInterface.OnClickListener() { 
      public void onClick(DialogInterface dialog, int item) { 
       Source.updateRecentDisplayed(allSourceItem.get(item)); 
       restartActivity(); 
      } 
     }); 
     AlertDialog alert = builder.create(); 
     alert.show(); 
    } 

    return super.onOptionsItemSelected(item); 
} 

// for creatting tabs Fragments 
public static class PlaceholderFragment extends Fragment { 
    /** 
    * The fragment argument representing the section number for this 
    * fragment. 
    */ 

    private GridView mGridView; 
    private ArticleAdapter mArticleAdapter; 
    private ArrayList<Article> mGridData = new ArrayList<Article>(); 
    private TextView tv; 

    private static final String ARG_SECTION_NUMBER = "section_number"; 

    @Override 
    public void onCreate(@Nullable Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
    } 

    public PlaceholderFragment() { 
    } 

    /** 
    * Returns a new instance of this fragment for the given section 
    * number. 
    */ 
    public static PlaceholderFragment newInstance(int sectionNumber) { 
     PlaceholderFragment fragment = new PlaceholderFragment(); 
     Bundle args = new Bundle(); 
     args.putInt(ARG_SECTION_NUMBER, sectionNumber); 
     fragment.setArguments(args); 
     return fragment; 
    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     View rootView = inflater.inflate(R.layout.fragment_tabbed, container, false); 
     tv = (TextView) rootView.findViewById(R.id.test_tv); 
     tv.setText("Page counter :: "+getArguments().getInt(ARG_SECTION_NUMBER)); 
     mGridView = (GridView) rootView.findViewById(R.id.article_grid); 
     update(mGridData); 
     return rootView; 
    } 

    public void update(ArrayList<Article> data){ 
     mArticleAdapter = new ArticleAdapter(getContext(),R.layout.aricle_grid_element,data); 
     mGridView.setAdapter(mArticleAdapter); 
    } 

} 

public class SectionsPagerAdapter extends FragmentPagerAdapter { 

    int tabsCount; 
    Source src; 
    public SectionsPagerAdapter(FragmentManager fm, int tabsCount, Source src) { 
     super(fm); 
     this.tabsCount = tabsCount; 
     this.src = src; 
    } 


    @Override 
    public Fragment getItem(int position) { 
     // getItem is called to instantiate the fragment for the given page. 
     // Return a PlaceholderFragment (defined as a static inner class below). 

     if(position == 0){ 
      runArticleService(position+1); 
      return PlaceholderFragment.newInstance(position + 1); 
     }else if (position == 1){ 
      runArticleService(position+1); 
      return PlaceholderFragment.newInstance(position + 1); 
     }else if (position == 2){ 
      runArticleService(position+1); 
      return PlaceholderFragment.newInstance(position + 1); 
     } 
     return null; 
    } 

    @Override 
    public int getCount() { 
     // Show 3 total pages. 
     return tabsCount; 
    } 

    @Override 
    public CharSequence getPageTitle(int position) { 
     switch (position) { 
      case 0: 
       return "SECTION 1"; 
      case 1: 
       return "SECTION 2"; 
      case 2: 
       return "SECTION 3"; 
     } 
     return null; 
    } 

    private void runArticleService(int tabNumber){ 
     Intent mServiceIntent = new Intent(getBaseContext(), ArticleService.class); 
     mServiceIntent.setData(Uri.parse(Asset.getSourceArticleURL(src.getUniqueId(),tabNumber))); 
     startService(mServiceIntent); 
    } 
} 

// broadcast receivers handle 
private class ArticleStateReceiver extends BroadcastReceiver 
{ 
    private ArticleStateReceiver() { 

    } 
    // Called when the BroadcastReceiver gets an Intent it's registered to receive 
    @Override 
    public void onReceive(Context context, Intent intent) { 
     String response = intent.getStringExtra(Asset.ARTICLE_EXTENDED_DATA_TYPE); 
     String sortType = intent.getStringExtra(Asset.ARTICLE_EXTENDED_DATA_SORT); 

     if(sortType.equals("TOP")){ 
      SectionsPagerAdapter sectionsPagerAdapter = (SectionsPagerAdapter) mViewPager.getAdapter(); 
      PlaceholderFragment placeholderFragment = (PlaceholderFragment) sectionsPagerAdapter.getItem(0); 
      placeholderFragment.update(Asset.getArticleObjectFromJSON(response.toString())); 
     }else if(sortType.equals("LATEST")){ 
      SectionsPagerAdapter sectionsPagerAdapter = (SectionsPagerAdapter) mViewPager.getAdapter(); 
      PlaceholderFragment placeholderFragment = (PlaceholderFragment) sectionsPagerAdapter.getItem(1); 
      placeholderFragment.update(Asset.getArticleObjectFromJSON(response.toString())); 
     }else if(sortType.equals("POPULAR")){ 
      SectionsPagerAdapter sectionsPagerAdapter = (SectionsPagerAdapter) mViewPager.getAdapter(); 
      PlaceholderFragment placeholderFragment = (PlaceholderFragment) sectionsPagerAdapter.getItem(2); 
      placeholderFragment.update(Asset.getArticleObjectFromJSON(response.toString())); 
     } 

    } 
} 

// Extra methods 
private int getNumberOfTabs(boolean top, boolean latest, boolean popular){ 
    if(top && latest && popular){ 
     return 3; 
    }else if(top && latest && !popular){ 
     return 2; 
    }else if(top && !latest && !popular){ 
     return 1; 
    }else{ 
     return 1; 
    } 
} 

private void setTabs(int tabCount){ 
    tabLayout.removeAllTabs(); 
    if(tabCount == 3){ 
     tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.tab_1_text))); 
     tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.tab_2_text))); 
     tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.tab_3_text))); 
    } 
    if(tabCount == 2){ 
     tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.tab_1_text))); 
     tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.tab_2_text))); 
    } 
    if(tabCount == 1){ 
     tabLayout.addTab(tabLayout.newTab().setText(getString(R.string.tab_1_text))); 
    } 
} 

private Source getRecentDisplayedData(){ 
    Source src = Source.getRecentDisplayed(); 
    if(src!=null){ 
     return src; 
    }else{ 
     src = Source.getRandom(); 
     Source.updateRecentDisplayed(src); 
     return Source.getRecentDisplayed(); 
    } 
} 

public void restartActivity(){ 
    Intent myIntent = new Intent(this, TabbedActivity.class); 
    startActivity(myIntent); 
    finish(); 
} 

} 

IntentService 

public class ArticleService extends IntentService { 

public String responseStr = null; 
public String urlStr = null; 

public ArticleService() { 
    super("ArticleService"); 
} 

@Override 
protected void onHandleIntent(Intent intent) { 
    Uri url = intent.getData(); 
    urlStr = url.toString(); 
    responseStr = Asset.fetchSourceDataFromURL(urlStr); 
    sendBroadcast(); 
} 

protected void sendBroadcast(){ 
    Intent localIntent = new Intent(Asset.ARTICLE_BROADCAST_ACTION).putExtra(Asset.ARTICLE_EXTENDED_DATA_TYPE,responseStr); 
    if(urlStr.toLowerCase().contains(Asset.SORT_TOP_URL.toLowerCase())){ 
     localIntent.putExtra(Asset.ARTICLE_EXTENDED_DATA_SORT,"TOP"); 
    }else if (urlStr.toLowerCase().contains(Asset.SORT_LATEST_URL.toLowerCase())){ 
     localIntent.putExtra(Asset.ARTICLE_EXTENDED_DATA_SORT,"LATEST"); 
    }else if (urlStr.toLowerCase().contains(Asset.SORT_POPULAR_URL.toLowerCase())){ 
     localIntent.putExtra(Asset.ARTICLE_EXTENDED_DATA_SORT,"POPULAR"); 
    } 
    LocalBroadcastManager.getInstance(this).sendBroadcast(localIntent); 
} 

} 

ошибок, что я не в состоянии понять,

01-26 07:57:29.789 1494-1494/in.co.yogender.newsnick.newsnick E/AndroidRuntime: FATAL EXCEPTION: main 
Process: in.co.yogender.newsnick.newsnick, PID: 1494 
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference 
at android.view.LayoutInflater.from(LayoutInflater.java:232) 
at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:181) 
at android.widget.ArrayAdapter.<init>(ArrayAdapter.java:166) 
at in.co.yogender.newsnick.newsnick.Adapters.ArticleAdapter.<init>(ArticleAdapter.java:0) 
at in.co.yogender.newsnick.newsnick.TabbedActivity$PlaceholderFragment.update(TabbedActivity.java:197) 
at in.co.yogender.newsnick.newsnick.TabbedActivity$ArticleStateReceiver.onReceive(TabbedActivity.java:273) 
at android.support.v4.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:297) 
at android.support.v4.content.LocalBroadcastManager.access$000(LocalBroadcastManager.java:46) 
at android.support.v4.content.LocalBroadcastManager$1.handleMessage(LocalBroadcastManager.java:116) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6077) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

Заранее спасибо

Answer 1

Я думаю, вы обновляете GridView из IntentService, где контекст является недействительным. Попробуйте вывести контекст из IntentService, как показано ниже, и дайте мне знать.

public void update(Context cont, ArrayList<Article> data){ 
    mArticleAdapter = new ArticleAdapter(cont, R.layout.aricle_grid_element,data); 
    mGridView.setAdapter(mArticleAdapter); 
}