Calling a Fragment method from a parent Activity

Question

I see in the Android Fragments Dev Guide that an  activity can call methods in a fragment by acquiring a reference to the Fragment from FragmentManager  using findFragmentById   or findFragmentByTag      The example that follows shows how to get a fragment reference  but not how to call specific methods in the fragment   Can anyone give an example of how to do this   I would like to call a specific method in a Fragment from the parent Activity   Thanks

User · Accepted Answer

not get the question exactly as it is too simple :

ExampleFragment fragment = (ExampleFragment) getFragmentManager().findFragmentById(R.id.example_fragment);
fragment.<specific_function_name>();

Update: For those who are using Kotlin

var fragment = supportFragmentManager.findFragmentById(R.id.frameLayoutCW) as WebViewFragment
fragment.callAboutUsActivity()

User · Answer

Too late for the question but will post my answer anyway for anyone still needs it  I found an easier way to implement this  without using fragment id or fragment tag  since that s what I was seeking for  First  I declared my Fragment in my ParentActivity class  MyFragment myFragment   Initialized my viewPager as usual  with the fragment I already added in the class above  Then  created a public method called scrollToTop in myFragment that does what I want to do from ParentActivity  let s say scroll my recyclerview to the top  public void scrollToTop        mMainRecyclerView smoothScrollToPosition 0      Now  in ParentActivity I called the method as below  try     myFragment scrollToTop     catch  Exception e      e printStackTrace

User · Answer

If you re using a support library  you ll want to do something like this   FragmentManager manager   getSupportFragmentManager    Fragment fragment   manager findFragmentById R id my fragment   fragment myMethod

User · Answer

First you create method  in your fragment like  public void name           in your activity you add this   add onCreate   method   myfragment fragment new myfragment     finally call the method where you want to call  add this  fragment method name      try this code

User · Answer

I don t know about Java  but in C   Xamarin Android  there is no need to look up the fragment everytime you need to call the method  see below   public class BrandActivity   Activity       MyFragment myFragment       protected override void OnCreate Bundle bundle                                      myFragment   new MyFragment                                    void someMethod                 myFragment MyPublicMethod             public class MyFragment   Android Support V4 App Fragment       public override void OnCreate Bundle bundle                                  public override View OnCreateView LayoutInflater inflater  ViewGroup container  Bundle bundle                                  public void MyPublicMethod                                     I think in Java you can do the same

User · Answer

I think the best is to check if fragment is added before calling method in fragment  Do something like this to avoid null exception    ExampleFragment fragment    ExampleFragment  getFragmentManager   findFragmentById R id example fragment   if fragment isAdded       fragment  lt specific function name gt

User · Answer

If you are using    import android app Fragment     Then use either   1    ExampleFragment fragment    ExampleFragment  getFragmentManager   findFragmentById R id example fragment    fragment specific function name       Where R id example fragment is most likely the FrameLayout id inside your xml layout   OR  2    ExampleFragment fragment    ExampleFragment  getFragmentManager   findFragmentByTag    FragTagName       fragment specific function name       Where FragTagName is the name u specified when u did   TabHost mTabHost newTabSpec    FragTagName         If you are using    import android support v4 app Fragment     Then use either   1    ExampleFragment fragment    ExampleFragment  getSupportFragmentManager   findFragmentById R id example fragment    fragment specific function name       OR  2    ExampleFragment fragment    ExampleFragment  getSupportFragmentManager   findFragmentByTag    FragTagName       fragment specific function name

User · Answer

you also call fragment method using interface like   first you create interface   public interface InterfaceName       void methodName        after creating interface you implement interface in your fragment   MyFragment extends Fragment implements InterfaceName        overide     void methodName                and you create the reference of interface in your activity   class Activityname extends AppCompatActivity       Button click      MyFragment fragment       protected void onCreate Bundle savedInstanceState            super onCreate savedInstanceState           setContentView R layout activity            click   findViewById R id button            fragment   new MyFragment             click setOnClickListener new View OnClickListener                  Override             public void onClick View v                   fragment methodName

User · Answer

From fragment to activty     YourActivityClassName getActivity    yourPublicMethod      From activity to fragment   FragmentManager fm   getSupportFragmentManager       if you added fragment via layout xml YourFragmentClass fragment     YourFragmentClass fm findFragmentById R id your fragment id   fragment yourPublicMethod      If you added fragment via code and used a tag string when you added your fragment  use findFragmentByTag instead   YourFragmentClass fragment    YourFragmentClass fm findFragmentByTag  yourTag

User · Answer

HomesFragment getSupportFragmentManager   findFragmentById R id fragment container   filterValidation

User · Answer

FragmentManager fm   getFragmentManager     MainFragment frag    MainFragment fm findFragmentById R id main fragment    frag  lt specific function name gt

User · Answer

If you re not using a support library Fragment  then do the following      FragmentName  getFragmentManager   findFragmentById R id fragment id   methodName      2  If you re using a support library Fragment  then do the following     FragmentName  getSupportFragmentManager   findFragmentById R id fragment id   methodName

[android] Calling a Fragment method from a parent Activity

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