Création d'un gridview dans un tablayout et tentative de mise à jour de Gridview avec un service Intent

Question

J'ai créé une mise en page à onglets dans une activité. Mon activité en tant que point suivant à prendre en compte
1. Le nombre d'onglets dépend du type de tri disponible pour un objet Source. Il peut y avoir trois onglets maximum, à savoir Top, Latest et populaire.
2. Chaque onglet contient une GridView et il doit être mis à jour lorsque IntentService obtient des données
3. L'utilisateur peut choisir la source de la barre d'outils
4. Lorsque nouvelle source est sélectionnée, le nombre d'onglets devraient être selon une nouvelle source et GridView devrait également mettre à jour en conséquence

TabbedActivity

TabbedActivity public class étend 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); 
} 

} 

erreur que je ne suis pas en mesure de comprendre

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) 

Merci à l'avance

Answer 1

je pense, vous mettez à jour GridView de IntentService où le contexte est nul. Essayez de tirer le contexte de IntentService comme ci-dessous et faites le moi savoir.

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