我的名字是Omar，我在javafx中编写了此代码，以便在场景0和场景1之间切换。 引入输入扫描仪激光条形码编号时（6590055780）
它从场景0更改为场景1，一旦进入场景1，如果用户按下按钮，则将更改为场景0。 但是当我编译这段代码时，它给了我以下错误

“线程“ JavaFX Application Thread”中的异常java.lang.illegalArgumentException：网格hgap = 10.0 alignment = CENTER已设置为另一个场景的根“

我不知道为什么会收到此错误，就像setOnKeypressed不允许我离开该错误一样，当我想从场景0切换到场景1时，出现了此错误消息，请按顺序感谢所有帮助解决这个问题。非常感谢你

这是代码

import javafx.application.Application;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.stage.Stage;
import javafx.event.EventHandler;
import javafx.scene.control.TextArea;

import javafx.scene.input.KeyEvent;

public class scannerinputfx2 extends Application {
////////////* public class*///////

public static  String salida;


@Override
public void start(Stage primaryStage){
primaryStage.setTitle("what's up");



//scene 0
GridPane grid = new GridPane();
grid.setalignment(Pos.CENTER);
grid.setHgap(10);
grid.setVgap(10);
grid.setPadding(new Insets(25,25,25));

Scene scene = new Scene(grid,300,275);
TextArea area = new TextArea();
TextField userTextField = new TextField();
//grid.add(userTextField,0);
//grid.add(area,1);
GridPane.setConstraints(userTextField,0);
GridPane.setConstraints(area,1);
grid.getchildren().addAll(area,userTextField);

//scene 1
GridPane grid1 = new GridPane();
grid1.setalignment(Pos.CENTER);
grid1.setHgap(10);
grid1.setVgap(10);
grid1.setPadding(new Insets(25,25));
Scene scene1 = new Scene(grid1,275);
Button btnfinal = new Button("Press button to get back");
GridPane.setConstraints(btnfinal,0);
grid1.getchildren().addAll(btnfinal);


btnfinal.setOnaction(actionEvent -> {   
scene1.setRoot(grid);
});

primaryStage.setScene(scene);

        primaryStage.show();


 userTextField.setOnKeypressed(new EventHandler<KeyEvent>() {
            public void handle(KeyEvent ke) {


                 area.setText( userTextField.getText());


if (userTextField.getText().equals("6590055780"))
            {
      System.out.println("The number is " + userTextField.getText());

           userTextField.setText("");
           scene.setRoot(grid1);
             }
           else 
             {
      System.out.println("The number is not the indicated");
            }

            }


        });


}








////////*Here finish primary stage/////////
 public static void main(String[] args) {
        launch(args);
    }



}