我正在尝试使用相同的控制器将文本字段中的StudentID设置为新FXML文件的新窗口的标签。但是我得到相同的空指针异常。如何做到这一点？我已经看到了FXML文件具有不同控制器的示例。但是当FXML文件具有相同的控制器时找不到解决方案。预先感谢。

@FXML private Label New_window_label;

 @FXML private void StudentID_Submit(actionEvent actionEvent) throws IOException {


        if ( Enter_StudentID.getText().matches("[s]\\d+") ){

            StudentID = Enter_StudentID.getText();

            New_window_label.setText(Enter_StudentID.getText());




            Stage stage = (Stage) b_StudentID_Submit.getScene().getWindow();
            stage.close();
            Stage menu_stage = new Stage();

            Parent root = FXMLLoader.load(getclass().getResource("/view/menu.fxml"));
            Scene scene = new Scene(root,1100,800 );
            menu_stage.setTitle("Main View Window");
            menu_stage.setScene(scene);
            menu_stage.show();


        } else{

            StudentID_label.setText("Enter Student ID");

            Alert alert = new Alert(Alert.AlertType.ERROR);
            alert.setTitle("Invalid Student ID");
            alert.setHeaderText("Please enter the student ID starting with 's' ");
            alert.showAndWait();


        }

    }