A beginners program in JavaFx

Before code

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class Main extends Application {

 public static void main(String[] args) {
  launch(args);
 }

 @Override
 public void start(Stage primaryStage) {
  primaryStage.setTitle("Problem 3 - Lab 0");
  GridPane grid = new GridPane();
  grid.setAlignment(Pos.CENTER);
  grid.setHgap(10);
  grid.setVgap(5);
  grid.setPadding(new Insets(25, 25, 25, 25));

  grid.add(new Label("Name"), 0, 1, 1, 1);
  grid.add(new Label("Street"), 2, 1, 1, 1);
  grid.add(new Label("City"), 4, 1, 1, 1);

  TextField nameTextField = new TextField();
  grid.add(nameTextField, 0, 2, 2, 1);

  TextField streetTextField = new TextField();
  grid.add(streetTextField, 2, 2, 2, 1);

  TextField cityTextField = new TextField();
  grid.add(cityTextField, 4, 2, 2, 1);

  grid.add(new Label("State"), 1, 3, 1, 1);
  grid.add(new Label("Zip"), 3, 3, 1, 1);

  TextField stateTextField = new TextField();
  grid.add(stateTextField, 1, 4, 2, 1);

  TextField zipTextField = new TextField();
  grid.add(zipTextField, 3, 4, 2, 1);

  Button btn = new Button("Submit");
  HBox btnHBox = new HBox();
  btnHBox.setAlignment(Pos.CENTER);
  HBox.setMargin(btn, new Insets(0, 0, 10, 0));
  btnHBox.getChildren().add(btn);
  

  btn.setOnAction(e -> {
   System.out.println(nameTextField.getText());
   System.out.println(streetTextField.getText());
   System.out.println(cityTextField.getText() + ", "
     + stateTextField.getText() + zipTextField.getText());
  });
  BorderPane borderPane = new BorderPane();
  borderPane.setCenter(grid);
  borderPane.setBottom(btnHBox);

  Scene scene = new Scene(borderPane, 500, 200);

  primaryStage.setScene(scene);

  primaryStage.show();
 }

}

after code