JAVAFX：控制器类中的字段值为'；无法正确保存/更新listview时出现问题？_Java_Listview_Javafx_Scenebuilder

JAVAFX：控制器类中的字段值为'；无法正确保存/更新listview时出现问题？

java listview javafx

JAVAFX：控制器类中的字段值为'；无法正确保存/更新listview时出现问题？,java,listview,javafx,scenebuilder,Java,Listview,Javafx,Scenebuilder,所以我用JavaFX制作了一个小程序来熟悉它我很确定，我对javafx的工作原理有一些基本的了解，但这似乎让我难以理解，因为我遇到了一些无法找到解决方案的问题。尽管在谷歌上对它们进行了彻底的研究目前我有一个使用eclipse和SceneBuilder1.1的设置（因为2.0给了我各种各样的麻烦）我有一个非常简单的设置，其中有一个主应用程序，加载初始主应用程序窗口 public class Main extends Application { @Override

所以我用JavaFX制作了一个小程序来熟悉它

我很确定，我对javafx的工作原理有一些基本的了解，但这似乎让我难以理解，因为我遇到了一些无法找到解决方案的问题。尽管在谷歌上对它们进行了彻底的研究

目前我有一个使用eclipse和SceneBuilder1.1的设置（因为2.0给了我各种各样的麻烦）

我有一个非常简单的设置，其中有一个主应用程序，加载初始主应用程序窗口

public class Main extends Application {
        @Override 
        public void start(final Stage stage) throws Exception { 
           Parent root = FXMLLoader.load(getClass().getResource("/application/ApplicationWindow.fxml"));        
            Scene scene = new Scene(root);
            stage.getIcons().add(new Image("/application/bug3.png"));
            stage.setResizable(true);
            stage.setTitle("Simple Bugtracker");
            stage.setMinHeight(500);
            stage.setMinWidth(800);
            stage.setScene(scene);
            stage.show();
        }        

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

它似乎工作得很好。然后，我创建了一个控制器类，它包含正确的fx:id'etgui元素作为字段值，运行良好，我可以用java代码操作它们

到目前为止，我有两个问题

1）当我从我的一个listview中删除某些内容时，我已经设法修复了更新问题，因此它通过添加if null场景立即将其从listview中删除。但是当我创建一个对象类型的新实例时，listview在我重新启动程序之前不会更新

2）其次，我在控制器类中遇到了一个简单的int字段值的问题，我想在im调用的方法中使用它的当前值（在scenebuilder的按钮上设置），但它似乎总是坚持认为，即使该值设置正确，它仍然是在启动期间实例化时的原始值

这是我相当大的控制器类

public class MyController implements Initializable {

    // Logic related fields
    public ProjectList<Project> projectList = new ProjectList<Project>();
    public int currentProjectIndex = -1;
    public Bug currentBug;

    // Listview buffers
    public ObservableList<Project> projectsListBuffer = FXCollections.observableArrayList();
    public ObservableList<Bug> unsolvedListBuffer = FXCollections.observableArrayList();
    public ObservableList<Bug> solvedListBuffer = FXCollections.observableArrayList();

    // GUI related fields

    @FXML public ListView<Project> projectsListView;
    @FXML public ListView<Bug> unsolvedListView;
    @FXML public ListView<Bug> solvedListView;


    @FXML public TextArea topDisplayArea;
    @FXML public Button btnCreateProject;

    @FXML public TextField titleFieldCreateProject;
    @FXML public TextArea descriptionAreaCreateProject;

    @FXML public AnchorPane createProjectWindow;
    @FXML public AnchorPane projectsListViewAnchor;

    @FXML public Label projectTitleLabel;
    @FXML public Button createBugButton;

    @FXML public TextField titleFieldCreateBug;
    @FXML public TextArea descriptionAreaCreateBug;

    public Stage createProjectStage;
//  public Stage createBugStage;


    @Override
    public void initialize(URL arg0, ResourceBundle arg1) {
        // load data from file system
        try {
            loadData();
        } catch (IOException e) {           
            e.printStackTrace();
        }
        // Instantiate gui field values
//      projectsListView = new ListView();
//      unsolvedListView = new ListView();
//      solvedListView = new ListView();
//
//
//      topDisplayArea = new TextArea();
//      btnCreateProject = new Button();
//
//      titleFieldCreateProject = new TextField();
//      descriptionAreaCreateProject = new TextArea();
//
//      createProjectWindow = new AnchorPane();
//      projectsListViewAnchor = new AnchorPane();
//
//      projectTitleLabel = new Label();
//      createBugButton = new Button();
//      
//      titleFieldCreateBug = new TextField();
//      descriptionAreaCreateBug = new TextArea();


        updateListBuffers();

        projectsListView.setPrefHeight( getScreenH() );
        projectsListView.setItems(projectsListBuffer);
        unsolvedListView.setPrefHeight( getScreenH() );
        unsolvedListView.setItems(unsolvedListBuffer);

        // settings on necessary gui items

        topDisplayArea.setPrefHeight( getScreenH() );
        topDisplayArea.setPrefWidth( getScreenW() );
        topDisplayArea.setEditable(false);
        topDisplayArea.setBackground(null); // something to be done here for transparent logo in background of all project descriptions etc.

        // ved dobbeltklik i projektlisten, vælg project og sæt titel
        projectsListView.setOnMouseClicked(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent click) {

                if (click.getClickCount() == 2) {
                    //Use ListView's getSelected Item
                    currentProjectIndex = projectsListView.getSelectionModel().getSelectedIndex();
                    Project currentProject = projectList.get(projectsListView.getSelectionModel().getSelectedIndex());
                    projectTitleLabel.setText(currentProject.getTitle());
                    System.out.println( "Selected project:"+currentProject.getTitle());                 
                    solvedListView.setItems(unsolvedListBuffer);
                    for (Bug b : currentProject.solvedBugs) {
                        System.out.println(b.getTitle()+"\n"+b.getErrorDescription());
                    }
                    updateListBuffers();
                }
            }
        });

        // ved dobbeltklik i uløste bugs listen, sæt top display område
        unsolvedListView.setOnMouseClicked(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent click) {
                if (click.getClickCount() == 2) {
                    //Use ListView's getSelected Item
                    currentBug = unsolvedListView.getSelectionModel().getSelectedItem();
                    topDisplayArea.setText(currentBug.getErrorDescription());
                }
            }
        });

        solvedListView.setOnMouseClicked(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent click) {
                if (click.getClickCount() == 2) {
                    //Use ListView's getSelected Item
                    currentBug = solvedListView.getSelectionModel().getSelectedItem();
                    topDisplayArea.setText(currentBug.getErrorDescription());
                }
            }
        });

        // custom listview cell for the projects listview
        projectsListView.setCellFactory(new Callback<ListView<Project>, ListCell<Project>>() {
            @Override
            public ListCell<Project> call(ListView<Project> p) {

                ListCell<Project> cell = new ListCell<Project>() {
                    @Override
                    protected void updateItem(Project t, boolean bln) {

                        super.updateItem(t, bln);

                        if (t != null) {
                            // program a custom cell with several items in it
                            Text text = new Text();
                            Text text2 = new Text();
                            text.wrappingWidthProperty().bind(p.widthProperty().subtract(15));
                            text.setText(t.getTitle());
                            text2.wrappingWidthProperty().bind(p.widthProperty().subtract(15));
                            text2.setText(t.getCreationDate().toLocaleString());
                            text.setFont(Font.font ("Verdana", 12));
                            text2.setFont(Font.font ("Verdana", 10));
                            text.setFill(Color.BLACK);
                            text2.setFill(Color.TEAL);
                            AnchorPane pane = new AnchorPane();     
                            pane.setPrefHeight(90);
                            pane.setPrefWidth(300);
                            ImageView imageView = new ImageView();
                            imageView.setImage(new Image("/application/project1.png"));
                            imageView.setFitHeight(60);
                            imageView.setFitWidth(60);
                            Image imageOk = new Image(getClass().getResourceAsStream("/application/selectionicon.png"));

                            Button deleteButton = new Button("Delete");
                            deleteButton.setLayoutX(233);
                            deleteButton.setLayoutY(60);
                            text.setLayoutX(70);
                            text.setLayoutY(30);
                            text2.setLayoutX(70);
                            text2.setLayoutY(50);
                            pane.getChildren().addAll(imageView, text, text2, deleteButton);

                            // delete actionevent           
                            deleteButton.setOnAction(new EventHandler<ActionEvent>() {
                                @Override 
                                public void handle(ActionEvent e) { 

                                    Alert alert = new Alert(AlertType.CONFIRMATION);
                                    alert.setTitle("Confirm deletion");
                                    alert.setHeaderText("Are you sure you want to delete this project?");
                                    Optional<ButtonType> result = alert.showAndWait();
                                    if (result.get() == ButtonType.OK){
                                        int selIndex = projectsListView.getSelectionModel().getSelectedIndex();
                                        if (selIndex>-1) {
                                            projectsListBuffer.remove(selIndex);
                                            projectList.remove(selIndex);                           
                                            projectsListView.setItems(projectsListBuffer);
                                            projectList.save();
                                        }

                                    } else {
                                        System.out.println("DENIED!!");
                                    }                                                               
                                }
                            });

                            setPrefWidth(0);
                            setGraphic(pane);
                        } else {
                            setText(null);
                            setGraphic(null);
                        }
                    }
                };
                return cell;
            }
        });

        // custom listview cell for the unsolved bugs listview
        unsolvedListView.setCellFactory(new Callback<ListView<Bug>, ListCell<Bug>>() {
            @Override
            public ListCell<Bug> call(ListView<Bug> p) {

                ListCell<Bug> cell = new ListCell<Bug>() {
                    @Override
                    protected void updateItem(Bug t, boolean bln) {
                        super.updateItem(t, bln);

                        if (t != null) {
                            // program a custom cell with several items in it
                            Text text = new Text();
                            Text text2 = new Text();
                            text.wrappingWidthProperty().bind(p.widthProperty().subtract(15));
                            text.setText(t.getTitle());
                            text2.wrappingWidthProperty().bind(p.widthProperty().subtract(15));
                            text2.setText(t.getCreationDate().toLocaleString());
                            text.setFont(Font.font ("Verdana", 12));
                            text2.setFont(Font.font ("Verdana", 10));
                            text.setFill(Color.BLACK);
                            text2.setFill(Color.TEAL);
                            AnchorPane pane = new AnchorPane();     
                            pane.setPrefHeight(90);
                            pane.setPrefWidth(300);
                            ImageView imageView = new ImageView();
                            imageView.setImage(new Image("/application/bug3.png"));
                            imageView.setFitHeight(60);
                            imageView.setFitWidth(60);
                            Image imageOk = new Image(getClass().getResourceAsStream("/application/selectionicon.png"));

                            Button selectButton = new Button("Select"); 
                            Button deleteButton = new Button("Delete");
                            selectButton.setLayoutX(233);
                            selectButton.setLayoutY(60);
                            deleteButton.setLayoutX(180);
                            deleteButton.setLayoutY(60);
                            text.setLayoutX(70);
                            text.setLayoutY(30);
                            text2.setLayoutX(70);
                            text2.setLayoutY(50);
                            pane.getChildren().addAll(imageView, text, text2);

                            deleteButton.setOnAction(new EventHandler<ActionEvent>() {
                                @Override 
                                public void handle(ActionEvent e) {                          
                                    projectsListBuffer.remove(projectsListView.getSelectionModel().getSelectedIndex());
                                    projectList.remove(projectsListView.getSelectionModel().getSelectedIndex());                            
                                    projectsListView.setItems(projectsListBuffer);
                                    projectList.save();
                                }
                            });

                            setPrefWidth(0);
                            setGraphic(pane);
                        } else {
                            setText(null);
                            setGraphic(null);
                        }
                    }
                };

                return cell;
            }
        });


    }

    // loads and show the create project window from it's fxml file (CreateProjectWindow.fxml)
    public void showCreateProjectWindow() {
        try {
            Parent root1 = FXMLLoader.load(getClass().getResource("/application/CreateProjectWindow.fxml"));    
            createProjectStage = new Stage();
            Scene scene = new Scene(root1);         
            createProjectStage.setScene(scene);  
            createProjectStage.setMinWidth(374);
            createProjectStage.setMinHeight(416);
            createProjectStage.setResizable(false);
            createProjectStage.show();          
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    // actionevent method that creates a new project   MANGLER AT FIKSE DET SÅ LISTVIEWET OPDATERER SIG MED DET SAMME
    public void createProject() {
        String title = titleFieldCreateProject.getText();
        String description = descriptionAreaCreateProject.getText();
        Project project = new Project(title, description, new Date());
        projectList.add(project);
        projectsListBuffer.add(project);
        projectList.save();
        updateListBuffers();
        projectsListView.setItems(projectsListBuffer);      

    }

    // loads and show the create project window from it's fxml file (CreateProjectWindow.fxml)
    public void showCreateBugWindow() {
        try {
            Parent root1 = FXMLLoader.load(getClass().getResource("/application/CreateBugWindow.fxml"));    
            createProjectStage = new Stage();
            Scene scene = new Scene(root1);         
            createProjectStage.setScene(scene);  
            createProjectStage.setMinWidth(374);
            createProjectStage.setMinHeight(416);
            createProjectStage.setResizable(false);
            createProjectStage.show();          
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    // actionevent method that creates a new bug   MANGLER AT FIKSE DET SÅ LISTVIEWET OPDATERER SIG MED DET SAMME
        public void createBug() {
            if (currentProjectIndex >-1) {
                String title = titleFieldCreateBug.getText();
                String description = descriptionAreaCreateBug.getText();
                System.out.println(title+"\n"+description);
                Bug bug = new Bug(title, description, new Date());
                projectList.get(currentProjectIndex).unsolvedBugs.add(bug);
                unsolvedListBuffer.add(bug);
                projectList.save();         
                updateListBuffers();
            } else {
                System.out.println("Failed creation.");
            }
        }

    // load, clear and reload buffers
    public void updateListBuffers() {
        if (currentProjectIndex>-1) {
            unsolvedListBuffer.clear();     
            for (int i=0; i<projectList.get(currentProjectIndex).unsolvedBugs.size(); i++) {            
                unsolvedListBuffer.add( projectList.get(currentProjectIndex).unsolvedBugs.get(i) );         
            }
            solvedListBuffer.clear();           
            for (int i=0; i<projectList.get(currentProjectIndex).solvedBugs.size(); i++) {          
                solvedListBuffer.add( projectList.get(currentProjectIndex).solvedBugs.get(i) );         
            }
//          unsolvedListView.setItems(null);
//          solvedListView.setItems(null);
            unsolvedListView.setItems(unsolvedListBuffer);
            solvedListView.setItems(solvedListBuffer);
        }   
        projectsListBuffer.clear();     
        for (int i=0; i<projectList.size(); i++) {          
            projectsListBuffer.add( projectList.get(i) );           
        }   
//      projectsListView.setItems(null);
        projectsListView.setItems(projectsListBuffer);

    }

    // file system related methods

    public void loadData() throws IOException {
        File fil = new File("Project_Data.dat");
        if ( !fil.exists() ) {
            fil.createNewFile();
            projectList = new ProjectList<Project>();
            projectList.save();
        } else {
            projectList = ProjectList.load();
        }
    }

    // practical methods

    public double getScreenH() {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        return screenSize.getHeight();
    }

    public double getScreenW() {
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        return screenSize.getWidth();
    }

}

您的问题几乎不可能像您所拥有的那样得到回答，因为您拥有的代码远远多于重现问题所需的代码，但您没有包含关键元素（如FXML文件）。最好从头开始创建一个小的、简单的、完整的示例来演示问题，而不是发布一个完整的控制器类

以下是一些适用于您所看到的问题的一般情况

下面是调用

fxmloader

的

load（…）

方法时发生的基本过程：

fxmloader

加载FXML文件

如果根元素具有

fx:controller

属性，并且没有控制器之前已设置，加载程序将字符串转换为

类。如果在加载器上设置了controllerFactory
，则将类
传递给控制器工厂的调用（…）
方法后，将检索构造函数。否则，将通过指定的类“无参数构造函数”实例化控制器。（如果之前已设置控制器，则加载过程将终止，并出现异常。）


加载程序解析FXML文件，创建指定的对象，并根据FXML结构将它们传递给彼此的各种集合方法。当创建了一个具有fx:id
属性的对象，并且（通过任何方式）创建了一个控制器时，控制器中带有与fx:id
值同名的@FXML
注释字段（如果存在）将初始化为该对象
如果已创建控制器，并且该控制器具有initialize（）
方法，则调用initialize（）
方法
load方法通过返回对根元素对应的对象的引用来完成
从编码的角度来看，这会带来一些后果：
声明和初始化带注释的字段，例如：
@FXML
private Label myLabel = new Label();

它总是多余的。如果正确设置了fx:id
，则在加载过程中将为myLabel
重新分配一个新值，并丢弃原始初始化值。更糟糕的是，如果未正确设置fx:id
，则使用myLabel
所做的任何操作都将应用于不属于场景图一部分的标签，因此您将获得难以调试的意外结果（基本上，操作将成功，但在UI中没有可见效果）。如果不初始化字段，则如果未正确设置fx:id
，它将立即失败，出现NullPointerException
，然后可以轻松调试
类似地，在initialize（）
方法中重新初始化@FXML
-注释字段总是一场灾难：
@FXML
private Label myLabel ;

public void initialize() {
    myLabel = new Label(...);
    // ...
}

在这种情况下，myLabel
首先由FXML加载程序初始化，但是当调用initialize（）
方法时，它会被不属于场景图的其他标签替换。因此，对myLabel
的操作将成功，但不会在UI中产生可见的效果
其次，在“标准”控制器设置中，您不在fxmloader
上调用setController
或setControllerFactory
，而是通过fx:controller
属性指定控制器类，每个fxmloader
创建相应控制器类的一个实例。从堆栈跟踪来看，它看起来像是ApplicationWindow.fxml
和CreateProjectWindow.fxml
使用相同的控制器类。这总是一个坏主意：当共享控制器类的每个实例与特定FXML文件定义的FXML元素相对应时，它们只会初始化带有@FXML
-注释的字段。显然，他们不会知道彼此的数据。您应该为每个FXML文件创建不同的控制器类。如果他们需要共享数据，请使用中概述的技术。通常，您可以通过在一个控制器中创建和公开一个可观察属性，并从另一个控制器中观察它来管理这一点，如下例所示
这里有一个简单的例子，我猜你的例子有一些相同的结构。这可能有助于研究和理解这一点。这里的所有内容都放在一个名为“application”的包中（包括FXML文件）
数据模型类别：Pers
@FXML
private Label myLabel ;

public void initialize() {
    myLabel = new Label(...);
    // ...
}

package application;

import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;

public class Person {
    private final StringProperty firstName = new SimpleStringProperty();
    private final StringProperty lastName = new SimpleStringProperty();

    public Person(String firstName, String lastName) {
        setFirstName(firstName);
        setLastName(lastName);
    }

    public final StringProperty firstNameProperty() {
        return this.firstName;
    }

    public final String getFirstName() {
        return this.firstNameProperty().get();
    }

    public final void setFirstName(final String firstName) {
        this.firstNameProperty().set(firstName);
    }

    public final StringProperty lastNameProperty() {
        return this.lastName;
    }

    public final String getLastName() {
        return this.lastNameProperty().get();
    }

    public final void setLastName(final String lastName) {
        this.lastNameProperty().set(lastName);
    }

    @Override
    public String toString() {
        return getFirstName() +" "+getLastName();
    }
}

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.layout.BorderPane?>
<?import javafx.scene.control.ListView?>
<?import javafx.scene.layout.HBox?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>

<BorderPane xmlns:fx="http://javafx.com/fxml/1"
    fx:controller="application.PersonListController">
    <center>
    <ListView fx:id="personList" />
</center>
    <bottom>
        <HBox spacing="5">
            <padding>
                <Insets top="10" bottom="10" left="10" right="10" />
            </padding>
            <Button text="New..." onAction="#newPerson" />
            <Button text="Edit..." onAction="#editPerson" fx:id="editButton" />
        </HBox>
    </bottom>
</BorderPane>

package application;

import javafx.beans.Observable;
import javafx.beans.binding.Bindings;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.ListView;
import javafx.stage.Stage;


public class PersonListController {
    @FXML
    private ListView<Person> personList ;
    @FXML
    private Button editButton ;

    public void initialize() {

        // list created so it fires updates if either the firstName or lastName change:
        ObservableList<Person> people = FXCollections.observableArrayList(person -> 
            new Observable[] {person.firstNameProperty(), person.lastNameProperty()});

        people.addAll(new Person("Jacob", "Smith"),
                new Person("Isabella", "Johnson"),
                new Person("Ethan", "Williams"),
                new Person("Emma", "Jones"),
                new Person("Michael", "Johnson"));
        personList.setItems(people);

        editButton.disableProperty().bind(
                Bindings.isNull(personList.getSelectionModel().selectedItemProperty()));
    }

    @FXML
    private void newPerson() throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("PersonEditor.fxml"));
        Parent root = loader.load();

        PersonEditorController controller = loader.getController();
        controller.personProperty().addListener((obs, oldPerson, newPerson) -> {
            if (newPerson != null) {
                personList.getItems().add(newPerson);
            }
        });

        showEditorWindow(root);
    }


    @FXML
    private void editPerson() throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("PersonEditor.fxml"));
        Parent root = loader.load();

        PersonEditorController controller = loader.getController();
        controller.setPerson(personList.getSelectionModel().getSelectedItem());

        showEditorWindow(root);
    }

    private void showEditorWindow(Parent root) {
        Scene scene = new Scene(root, 350, 200);
        Stage stage = new Stage();
        stage.initOwner(personList.getScene().getWindow());
        stage.setScene(scene);
        stage.show();
    }

}

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.layout.GridPane?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.HBox?>
<?import javafx.geometry.Insets?>
<?import javafx.scene.control.Button?>

<GridPane xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.PersonEditorController">
    <Label text="First Name:" GridPane.columnIndex="0"
        GridPane.rowIndex="0" />
    <Label text="Last Name:" GridPane.columnIndex="0"
        GridPane.rowIndex="1" />
    <TextField fx:id="firstNameTF" GridPane.columnIndex="1"
        GridPane.rowIndex="0" />
    <TextField fx:id="lastNameTF" GridPane.columnIndex="1"
        GridPane.rowIndex="1" />
    <HBox GridPane.columnIndex="0" GridPane.rowIndex="2"
        GridPane.columnSpan="2" spacing="5">
        <padding>
            <Insets top="5" bottom="5" left="5" right="5" />
        </padding>
        <Button text="OK" onAction="#submit" />
        <Button text="Cancel" onAction="#cancel" />
    </HBox>
</GridPane>

package application;

import javafx.beans.property.ObjectProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.fxml.FXML;
import javafx.scene.control.TextField;

public class PersonEditorController {
    @FXML
    private TextField firstNameTF ;
    @FXML
    private TextField lastNameTF ;

    private final ObjectProperty<Person> person = new SimpleObjectProperty<>();

    public ObjectProperty<Person> personProperty() {
        return person;
    }
    public final Person getPerson() {
        return personProperty().get();
    }
    public final void setPerson(Person person) {
        personProperty().set(person);
    }

    public void initialize() {
        personProperty().addListener((obs, oldPerson, newPerson) -> {
            if (newPerson != null) {
                firstNameTF.setText(newPerson.getFirstName());
                lastNameTF.setText(newPerson.getLastName());
            }
        });
    }

    @FXML
    private void submit() {
        if (person.get() == null) {
            person.set(new Person(firstNameTF.getText(), lastNameTF.getText()));
        } else {
            person.get().setFirstName(firstNameTF.getText());
            person.get().setLastName(lastNameTF.getText());
        }
        close();
    }

    @FXML
    private void cancel() {
        close();
    }

    private void close() {
        firstNameTF.getScene().getWindow().hide();
    }
}

package application;

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.layout.BorderPane;
import javafx.fxml.FXMLLoader;


public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            BorderPane root = (BorderPane)FXMLLoader.load(getClass().getResource("PersonList.fxml"));
            Scene scene = new Scene(root,400,400);
            primaryStage.setScene(scene);
            primaryStage.show();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

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