ottiene il frammento per tag o id da tablayout, android

Question

io uso this tutorial per creare la scheda. e ora ho un recyclerview in ogni frammento e voglio notificarli dal mainactivity. come accedere all'adattatore in frammento?

io uso questo per chiamata metodo RefreshData() in frammento:

TabFragment1 tabFragment = (TabFragment1) getSupportFragmentManager().findFragmentByTag(TabFragment1.class.getSimpleName()); 
if (tabFragment != null) { 
        tabFragment.refreshData(); 
       } 

ma nulla ritorno.

mainActivity:

TabLayout  tabLayout = (TabLayout) findViewById(R.id.tabLayout); 
tabLayout.addTab(tabLayout.newTab().setText("Tab1")); 
tabLayout.addTab(tabLayout.newTab().setText("Tab2")); 


final PagerAdapter adapter = new PagerAdapter 
     (getSupportFragmentManager(), tabLayout.getTabCount()); 
viewPager.setAdapter(adapter); 
viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout)); 
tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() { 
    @Override 
    public void onTabSelected(TabLayout.Tab tab) { 
     viewPager.setCurrentItem(tab.getPosition()); 
    } 

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

    } 

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

    } 
}); 

PagerAdapter:

public class PagerAdapter extends FragmentStatePagerAdapter { 
int mNumOfTabs; 

public PagerAdapter(FragmentManager fm, int NumOfTabs) { 
    super(fm); 
    this.mNumOfTabs = NumOfTabs; 
} 

@Override 
public Fragment getItem(int position) { 

    switch (position) { 
     case 0: 
      TabFragment1 tab1 = new TabFragment1(); 
      return tab1; 
     case 1: 
      TabFragment2 tab2 = new TabFragment2(); 
      return tab2; 
     case 2: 
      TabFragment3 tab3 = new TabFragment3(); 
      return tab3; 
     case 3: 
      TabFragment4 tab4 = new TabFragment4(); 
      return tab4; 
     default: 
      return null; 
    } 
} 

@Override 
public int getCount() { 
    return mNumOfTabs; 
} 
} 

Uno dei myTabFragment:

public CardAdapter adapter; 
     @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { 
     RecyclerView v = (RecyclerView) inflater.inflate(R.layout.tab_fragment_1, container, false); 
     SetupRecycleView(v); 
     return v; 
    } 
    public void refreshData() { 
     adapter.notifyDataSetChanged(); 

    } 
    void SetupRecycleView(RecyclerView recList) { 
     recList.setHasFixedSize(true); 
     LinearLayoutManager llm = new LinearLayoutManager(G.context); 
     llm.setOrientation(LinearLayoutManager.VERTICAL); 
     //recList.setLayoutManager(new GridLayoutManager(G.context, 2)); 
     recList.setLayoutManager(llm); 
     List<StructGhaza> ghazas = StructGhaza.getAllGhaza("2"); 
     adapter = new CardAdapter(ghazas); 
     recList.setAdapter(adapter); 
    } 

Il CardAdapter:

public class CardAdapter extends  RecyclerView.Adapter<CardAdapter.GhazaViewHolder> { 

private List<StructGhaza> ghazas; 

public CardAdapter(List<StructGhaza> ghazaList) { 
    this.ghazas = ghazaList; 
} 

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

@Override 
public void onBindViewHolder(GhazaViewHolder ghazaViewHolder, int position) { 

    StructGhaza ghaza = ghazas.get(position); 
    ghazaViewHolder.vTitle.setText(ghaza.Name); 
    //----Load Image 
    Glide.with(G.context) 
      .load(ghaza.Aks) 
      .placeholder(R.drawable.loading_spinner) 
      .crossFade() 
      .into(ghazaViewHolder.itemImg); 
    //--------------- 
    ghazaViewHolder.Rate.setRating(ghaza.Star); 
    ghazaViewHolder.sampleLayout.setHoverView(ghazaViewHolder.hover); 
    ghazaViewHolder.sampleLayout.addChildAppearAnimator(ghazaViewHolder.hover, R.id.tvHover, Techniques.FlipInX); 
    ghazaViewHolder.sampleLayout.addChildDisappearAnimator(ghazaViewHolder.hover, R.id.tvHover, Techniques.FlipOutX); 
} 

@Override 
public GhazaViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) { 
    View itemView = LayoutInflater. 
      from(viewGroup.getContext()). 
      inflate(R.layout.fragment_carditem, viewGroup, false); 

    return new GhazaViewHolder(itemView); 
} 

public static class GhazaViewHolder extends RecyclerView.ViewHolder { 
    protected TextView vTitle; 
    protected BlurLayout sampleLayout; 
    protected View hover; 
    protected ImageView itemImg; 
    protected RatingBar Rate; 

    public GhazaViewHolder(View v) { 
     super(v); 
     sampleLayout = (BlurLayout) v.findViewById(R.id.sample); 
     itemImg = (ImageView) v.findViewById(R.id.item_img); 
     hover = LayoutInflater.from(G.context).inflate(R.layout.fragment_hover, null); 
     vTitle = (TextView) v.findViewById(R.id.titleTv); 
     Rate = (RatingBar) v.findViewById(R.id.rating); 
    } 
} 
} 

Answer 1

EDIT: Dopo molti test, la risposta precedente funziona con Android < 21, ma per Android> 21 è un po 'strano, non sembra funzionare nello stesso modo.

Infine, ho risolto così, e funziona ovunque:

l'adattatore:

HashMap<Integer, Fragment> mPageReferenceMap = new HashMap<>(); 
@Override 
public Object instantiateItem(ViewGroup container, int position) { 
    Fragment fragment = (Fragment) super.instantiateItem(container, position); 
    mPageReferenceMap.put(position, fragment); 
    return fragment; 
} 

@Override 
public void destroyItem(ViewGroup container, int position, Object object) { 
    super.destroyItem(container, position, object); 
    mPageReferenceMap.remove(position); 
} 
public Fragment getFragment(int key) { 
    return mPageReferenceMap.get(key); 
} 

e vi invito getFragment dove volete nella vostra attività come quella:

int index = viewPager.getCurrentItem(); 
ViewPagerAdapter adapter = ((ViewPagerAdapter)viewPager.getAdapter()); 
final YourFragment tabFragment = (YourFragment) adapter.getFragment(index); 

---

RISPOSTA PRECEDENTE:

Attenzione: non funziona proprio con Android> 21

---

Ho avuto lo stesso problema. Infine, non ho usato id o tag.

Invece di usare:

CustomFragment customFragment = (CustomFragment) getSupportFragmentManager().findFragmentByTag(getString(R.string.fragment_custo_tag)); 

uso questo:

CustomFragment customFragment = (CustomFragment) getSupportFragmentManager().getFragments().get(0); 

per ottenere un'istanza di CustomFragment.

Ho messo get (0) come la posizione dell'istanza di CustomFragment è a zero.

Ho riscontrato questo problema qui: Set and get using tag a fragment in android