Java DatePicker返回Null

Question

我在JTabbedPane中有两个JPanel。每个JPanel都有两个DatePickers。当我编写第一个JPanel时，每个DatePickers工作正常。但是，一旦我在另一个类中添加了另外两个DatePickers，前两个DatePickers就不再起作用了。当我尝试返回所选日期（使用datePicker.getValue（））时，第一个类中的DatePickers返回值null。但是，后来的DatePickers运行得很好。

有谁知道为什么会这样？

BudgetTab类中的特定代码（有问题的类）：

jfxpanel = new JFXPanel();
jfxpanel2 = new JFXPanel();
jfxpanel.setBounds(460, 152, 265, 40);
jfxpanel2.setBounds(460, 276, 265, 40);

Platform.runLater(new Runnable(){
    @Override
    public void run(){
        initFX(jfxpanel);
        initFX2(jfxpanel2);
    }
});

budgetPanel.add(jfxpanel);
budgetPanel.add(jfxpanel2);

private void initFX(JFXPanel panel){
        Scene scene = createScene();
        panel.setScene(scene);
    }

    private void initFX2(JFXPanel panel){
        Scene scene = createScene2();
        panel.setScene(scene);
    }

    private static Scene createScene(){
        Group root = new Group();
        Scene scene = new Scene(root);
        dp = new DatePicker();
        dp.setEditable(false);
        root.getChildren().add(dp);
        return scene;
    }

    private static Scene createScene2(){
        Group root = new Group();
        Scene scene = new Scene(root);
        dp2 = new DatePicker();
        dp2.setEditable(false);
        root.getChildren().add(dp2);

        return scene;
    }

时间轴课程中的特定代码：

startDatePanel = new JFXPanel();
        startDatePanel.setForeground(panelColor);
        endDatePanel = new JFXPanel();
        endDatePanel.setForeground(panelColor);

        Platform.runLater(new Runnable(){
        @Override
            public void run(){
                initStartDate(startDatePanel);
                initEndDate(endDatePanel);
            }
        });  

public void initStartDate(JFXPanel panel){

        Scene scene = createStartDateScene();
        panel.setScene(scene);
    }

    private static Scene createStartDateScene(){
        Group root = new Group();
        Scene scene = new Scene(root);
        startDatePicker = new DatePicker();
        startDatePicker.setEditable(false);
        root.getChildren().add(startDatePicker);
        return scene;

    }

    public void initEndDate(JFXPanel panel){
        Scene scene = createEndDateScene();
        panel.setScene(scene);
    }

    private static Scene createEndDateScene(){
        Group root = new Group();
        Scene scene = new Scene(root);
        endDatePicker = new DatePicker();
        endDatePicker.setEditable(false);
        root.getChildren().add(endDatePicker);
        return scene;
    }