What generates "cannot be referenced from static context" when static keyword is not used in the class?

Question

I get the Non-static method 'getSupportFragmentManager()' cannot be referenced from static context error for the following code:

import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentActivity;
.
.
.
public class MedicalInformationFragment extends Fragment implements FragmentNameProvider, ConfirmDialogFragment.ConfirmDialogListener{
.
.
.
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    Log.d(TAG, "Entered: onCreate");
    first = true;
    if(getArguments() != null) {
        petId = getArguments().getInt(PET_ID_KEY);
        Log.d(TAG, "Pet ID is: " + petId);
        sMedicalInformationViewModel = ViewModelProviders.of(this).get(MedicalInformationViewModel.class);
        FragmentManager fm = FragmentActivity.getSupportFragmentManager();
        if(fm != null) {
            thisFragment = fm.findFragmentById(R.id.fragment_container);
            Log.d(TAG, "thisFragment is: " + thisFragment);
        }else{
            Log.d(TAG, "Error: fm == null");
        }
    }else{
        Log.d(TAG, "Error: getArguments() == null");
    }
}
.
.
.
}

However, the keyword 'static' is never used in the class, anywhere.

I am following the API for using getSupportFragmentManager(). I had used getFragmentManager but was told that android.app.Fragment was deprecated in API level 28.and to use the Support Library Fragment for consistent behavior across all devices and access to Lifecycle, but found that this package is part of the Android support library which is no longer maintained. The support library has been superseded by AndroidX which is part of Jetpack.

So, here I am, following what I believe are the directives of the Android API and getting an error that I don't understand. What would generate this error when the 'static' keyword is not used?

Answer 1

You are calling an instance method (getSupportFragmentManager()) on a class (FragmentActivity), not on an instance. The "static context" is FragmentActivity.

To get a FragmentManager for your Fragment, try getParentFragmentManager():

FragmentManager fm = getParentFragmentManager();

If that does not seem to exist, you are on an older version of the AndroidX libraries, before that method existed. In that case, use getFragmentManager():

FragmentManager fm = getFragmentManager();