JavaFX - 如何使用GridPane来布局输入形式

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ChoiceBox;
import javafx.scene.control.DatePicker;
import javafx.scene.control.Label;
import javafx.scene.control.TextArea;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class Main extends Application {   
    Label fNameLbl = new Label("First Name:");
    Label lNameLbl = new Label("Last Name:");
    Label bDateLbl = new Label("Birth Date:");
    Label genderLbl = new Label("Gender:");
    
    TextField fNameFld = new TextField();
    TextField lNameFld = new TextField();
    DatePicker bDateFld = new DatePicker(); 
    ChoiceBox<String> genderFld = new ChoiceBox<>();    
    TextArea dataFld = new TextArea();
    
    Button saveBtn = new Button("Save");
    Button closeBtn = new Button("Close");

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

    @Override
    public void start(Stage stage) throws Exception {
        genderFld.getItems().addAll("Male", "Fenale", "Unknwon");
        
        dataFld.setPrefColumnCount(30);
        dataFld.setPrefRowCount(5);
        
        GridPane grid = new GridPane(); 
        grid.setHgap(5);
        grid.setVgap(5);
        
        // Place the controls in the grid   
        grid.add(fNameLbl, 0, 0);  // column=0, row=0
        grid.add(lNameLbl, 0, 1);  // column=0, row=1
        grid.add(bDateLbl, 0, 2);  // column=0, row=2
        grid.add(genderLbl, 0, 3); // column=0, row=3
            
        grid.add(fNameFld, 1, 0);  // column=1, row=0
        grid.add(lNameFld, 1, 1);  // column=1, row=1
        grid.add(bDateFld, 1, 2);  // column=1, row=2
        grid.add(genderFld, 1, 3); // column=1, row=3
        grid.add(dataFld, 1, 4, 3, 2); // column=1, row=4, colspan=3, rowspan=3
        
        VBox buttonBox = new VBox(saveBtn, closeBtn);
        saveBtn.setMaxWidth(Double.MAX_VALUE);
        closeBtn.setMaxWidth(Double.MAX_VALUE);
        
        grid.add(buttonBox, 2, 0, 1, 2); // column=2, row=0, colspan=1, rowspan=2

        saveBtn.setOnAction(e -> showData());
        
        closeBtn.setOnAction(e -> stage.hide());
        
        Scene scene = new Scene(grid);
        stage.setScene(scene);
        stage.setTitle("Person Details");
        stage.sizeToScene();
        stage.show();
    }
    
    private void showData() {
        String data = "First Name = " + fNameFld.getText() + 
                      "\nLast Name=" + lNameFld.getText() + 
                      "\nBirth Date=" + bDateFld.getValue() + 
                      "\nGender=" + genderFld.getValue();
        dataFld.setText(data);
    }
}