How can i use setContentView method in fragment?

Question

I'm working on a small project...project works with maps, But there is a problem with setContentView method it does not work when i extend Fragment instead of FragmentActivity . Note : i need extends Fragment not Fragment Activity because the code displayed in code section is just a small part of project. In my original project if i change Fragment to FragmentActivity there are problems that appear in another class.

public class MapsActivity extends Fragment implements OnMapReadyCallback,LocationListener,GoogleMap.OnMarkerClickListener{


    private GoogleMap mMap;
    private DatabaseReference mUsers;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //Dosn't Work with Fragment Extends ?!
        setContentView(R.layout.activity_maps);
        SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
        mUsers= FirebaseDatabase.getInstance().getReference("Users");

    }


    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;
        googleMap.setOnMarkerClickListener(this);
        mUsers.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                for (DataSnapshot s : dataSnapshot.getChildren()){
                    UserInformation user = s.getValue(UserInformation.class);
                    assert user != null;
                    LatLng location = new LatLng(user.latitude,user.longitude);
                    mMap.addMarker(new MarkerOptions().position(location).title(user.name)).setIcon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_YELLOW));
                }

            }
            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
            }
        });
    }



    @Override
    public void onLocationChanged(Location location) {
    }
    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
    }
    @Override
    public void onProviderEnabled(String provider) {
    }
    @Override
    public void onProviderDisabled(String provider) {
    }
    @Override
    public boolean onMarkerClick(Marker marker) {
        return false;
    }
}

I expect application runs normally and show different marks on map based on data in firebase, But The app does not work. Note : if i change Fragment to FragmentActivity it works without problems..

I tried on create view but application dose not working "app has stopped"

public class MapsActivity extends Fragment implements OnMapReadyCallback,LocationListener,GoogleMap.OnMarkerClickListener{


private GoogleMap mMap;
private DatabaseReference mUsers;

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}


@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.activity_maps, container, false);
    SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
    mUsers= FirebaseDatabase.getInstance().getReference("Users");
    return view;
}

@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;
    googleMap.setOnMarkerClickListener(this);
    mUsers.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            for (DataSnapshot s : dataSnapshot.getChildren()){
                UserInformation user = s.getValue(UserInformation.class);
                assert user != null;
                LatLng location = new LatLng(user.latitude,user.longitude);
                mMap.addMarker(new MarkerOptions().position(location).title(user.name)).setIcon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_YELLOW));
            }

        }
        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {
        }
    });
}



@Override
public void onLocationChanged(Location location) {
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
@Override
public boolean onMarkerClick(Marker marker) {
    return false;
}

When i change fragment to fragment activity there is an error is this line in another activity

getSupportFragmentManager().beginTransaction().replace(R.id.container,new HomeFragment()).commit();

when HomeFragment was extends Fragment there is no error, But when i change it to Fragment Activity, error appear in [new HomeFragment()].

Answer 1

Use onCreateView method as a starting point for Fragments. You should think about a fragment as a layout itself, not a container that needs a view to be represented.

@Override
public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.activity_maps, container, false);
    // ...
    return view;
}

Answer 2

I found solution for this problem, I should override 2 methods, onViewCreated , onCreateView then the code should putted inside onCreate must be in onViewCreated like this

public class HomeFragment extends Fragment implements OnMapReadyCallback,LocationListener,GoogleMap.OnMarkerClickListener  {


public GoogleMap mMap;
public DatabaseReference mUsers;

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);

    SupportMapFragment mapFragment = (SupportMapFragment) getChildFragmentManager().findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);
    mUsers= FirebaseDatabase.getInstance().getReference("Users");

}


@NonNull
@Override
public View onCreateView(@NonNull LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    return inflater.inflate(R.layout.fragment_home, container, false);

}

@Override
public void onMapReady(GoogleMap googleMap) {

mMap = googleMap;
        googleMap.setOnMarkerClickListener(this);
        mUsers.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                for (DataSnapshot s : dataSnapshot.getChildren()){
                    UserInformation user = s.getValue(UserInformation.class);
                    assert user != null;
                    LatLng location = new LatLng(user.latitude,user.longitude);
                    mMap.addMarker(new MarkerOptions().position(location).title(user.name)).setIcon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_YELLOW));
                }

            }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
            }
        });

}