TextFields not updating

New to android development and been trying to follow a tutorial for a gps location app in android studio, but for some reason the text field are not updating.

Here is the tutorial i have been following :- [Android Studio Tutorial - Build a GPS App]1

................................................................................................................................................................................................................................................................... Here is the code :-

public class MainActivity extends AppCompatActivity {

TextView longi,lat;
Switch share;

// google play service api
FusedLocationProviderClient fusedLocationProviderClient;
// location request service
LocationRequest locationRequest;
private static final int sETINTERVAL=30;
private static final int fASTESTINTERVAL=5;
public static final int rEQUESTCODE=1;

@RequiresApi(api = Build.VERSION_CODES.M)
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    longi = findViewById(R.id.longi);
    lat   = findViewById(R.id.lat);
    share = findViewById(R.id.share);

    locationRequest = LocationRequest.create();

    locationRequest.setInterval(1000 * sETINTERVAL);
    locationRequest.setFastestInterval(1000 * fASTESTINTERVAL);
    locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

    share.setOnClickListener(v -> {
        if(share.isChecked()){
            share.setText("ON");
            updateGPS();
        }
        else{
            share.setText("OFF");
        }
    });
}

@RequiresApi(api = Build.VERSION_CODES.M)
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    super.onRequestPermissionsResult(requestCode, permissions, grantResults);

    switch (requestCode){
        case rEQUESTCODE:
            if(grantResults[0] == PackageManager.PERMISSION_GRANTED){
                updateGPS();
            }
            else{
                Toast.makeText(this, "Requires location permission", Toast.LENGTH_SHORT).show();
                finish();
            }
            break;
        default:
            throw new IllegalStateException("Unexpected value: " + requestCode);
    };
}


@RequiresApi(api = Build.VERSION_CODES.M)
private void updateGPS(){
    fusedLocationProviderClient = LocationServices.getFusedLocationProviderClient(MainActivity.this);

    if(ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED){
        fusedLocationProviderClient.getLastLocation().addOnSuccessListener(this, new OnSuccessListener<Location>() {
            @Override
            public void onSuccess(Location location) {
                updateUI(location);
            }
        });
    }
    else{
        requestPermissions(new String[]{Manifest.permission.ACCESS_FINE_LOCATION},rEQUESTCODE);
    }
}

private void updateUI(Location location){
    lat.setText(String.valueOf(location.getLatitude()));
    longi.setText(String.valueOf(location.getLongitude()));
}

}