Problems with localization request

Question

Hello, good afternoon! I am having problems with the return of my location in my code (it is also not asking permission to the user)

CODE OF ACTIVITY

public class GPSActivity extends AppCompatActivity implements LocationListener {
private TextView tv_gpsTexto;
private LocationManager locationManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_gps);
    SetToolbar();

    tv_gpsTexto = (TextView) findViewById(R.id.tv_gpsTexto);
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);

    boolean isGPSEnabled = locationManager
            .isProviderEnabled(LocationManager.GPS_PROVIDER);

    locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);

    //Teste  para permissão
    if ((ContextCompat.checkSelfPermission(GPSActivity.this, android.Manifest.permission.ACCESS_COARSE_LOCATION) == PackageManager.PERMISSION_GRANTED)
            && (ContextCompat.checkSelfPermission(GPSActivity.this, Manifest.permission.ACCESS_FINE_LOCATION) == PackageManager.PERMISSION_GRANTED)){

        //Requisição da permissão no celular (você vai dar acesso)
        ActivityCompat.requestPermissions(GPSActivity.this,
                new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, 100);

        //Envia a localização para a plataforma
        Location location = locationManager.getLastKnownLocation(locationManager.NETWORK_PROVIDER);
        onLocationChanged(location);
        return;
    }

}

@Override
public void onLocationChanged(Location location) {
    //Pegar Latitude e Longitude
    Log.d("TagPermissao3", "O USUÁRIO MUDOU A LOCALIZACAO");
    double longitude = location.getLongitude();
    double latitude = location.getLatitude();

    tv_gpsTexto.setText("Logitude: " + longitude + "\n" + "Latitude: " + latitude);
}

private void SetToolbar() {
    TextView tite;
    tite = (TextView) findViewById(R.id.tite);
    tite.setTypeface(GetFont.BoldFont(this));
    tite.setText("GPS");
    ImageView reply = (ImageView) findViewById(R.id.reply);
    reply.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            finish();

        }
    });
}

}

And, I have declared the following permissions in the Manifest

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />