Android getting fragment that is in FragmentPagerAdapter

Question

I have following problem: I have one activity in which I have two tabs which are made both as fragments using FragmentPagerAdapter In some moment I would like to change View of one of these fragments, but I am not able to findFragmentById() or findFragmentByTag() I am unable to set id, because I am not declaring Fragment in XML, because of the FragmentPagerAdapter And when I am trying to set tag I am getting following problem:

08-15 21:46:23.805: E/AndroidRuntime(9297): java.lang.IllegalStateException: Can't  change tag of fragment Companies{416d7b78 id=0x7f04002e companies}: was companies now android:switcher:2130968622:1 

My code of the pager FragmentPagerAdapter:

public class TabsAdapter extends FragmentPagerAdapter implements    ActionBar.TabListener, ViewPager.OnPageChangeListener {     private final FragmentActivity mContext;     private final ActionBar mActionBar;     private final ViewPager mViewPager;     private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>();       final class TabInfo {         private final Class<?> clss;         private final Bundle args;          TabInfo(Class<?> _class, Bundle _args) {             clss = _class;             args = _args;         }     }      public TabsAdapter(SherlockFragmentActivity activity, ViewPager pager) {         super(activity.getSupportFragmentManager());         mContext = activity;         mActionBar = activity.getSupportActionBar();         mViewPager = pager;         mViewPager.setAdapter(this);         mViewPager.setOnPageChangeListener(this);     }      public void addTab(ActionBar.Tab tab, Class<?> clss, Bundle args) {         TabInfo info = new TabInfo(clss, args);         tab.setTag(info);         tab.setTabListener(this);         mTabs.add(info);         mActionBar.addTab(tab);         notifyDataSetChanged();     }      @Override     public int getCount() {         return mTabs.size();     }      @Override     public Fragment getItem(int position) {         TabInfo info = mTabs.get(position);         FragmentTransaction ft=mContext.getSupportFragmentManager().beginTransaction();         Fragment fragment=Fragment.instantiate(mContext, info.clss.getName(), info.args);          if(position==1){             ft.add(mViewPager.getId(), fragment, "companies");         }else{             ft.add(mViewPager.getId(), fragment);         }         Log.v("FRAGMENT ID", "fragment tag: "+fragment.getTag());         ft.commit();         Log.v("FRAGMENT ID", "fragment tag: "+fragment.getTag());         return fragment;     }      @Override     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {     }      @Override     public void onPageSelected(int position) {         mActionBar.setSelectedNavigationItem(position);         new Thread(new Runnable() {              @Override             public void run() {                 MainActivity.this.hideKeyboard();              }         }).start();      }      @Override     public void onPageScrollStateChanged(int state) {     }      @Override     public void onTabSelected(Tab tab, FragmentTransaction ft) {         Object tag = tab.getTag();         for (int i = 0; i < mTabs.size(); i++) {             if (mTabs.get(i) == tag) {                 mViewPager.setCurrentItem(i);                                }         }       }      @Override     public void onTabUnselected(Tab tab, FragmentTransaction ft) {       }      @Override     public void onTabReselected(Tab tab, FragmentTransaction ft) {     } } 

Thank you in advance for your answers.

Answer 1

The Fragments supplied by the FragmentPagerAdapter are auto-tagged when they're instantiated. You can retrieve the tag with this method:

private static String makeFragmentName(int viewPagerId, int index) {      return "android:switcher:" + viewPagerId + ":" + index; } 

Reference: reusing fragments in a fragmentpageradapter

Answer 2

With this function you can find the fragment by pager adapter position.

public Fragment findFragmentByPosition(int position) {     FragmentPagerAdapter fragmentPagerAdapter = getFragmentPagerAdapter();     return getSupportFragmentManager().findFragmentByTag(             "android:switcher:" + getViewPager().getId() + ":"                     + fragmentPagerAdapter.getItemId(position)); } 

Sample code for v4 support api.