当我在 DatePicker 中选择日期时如何获取文本字段值

Question

我将其设为日期选择器 class，它扩展了 JFXPanel，因此我可以在我的 swing 应用程序中使用日期选择器功能。一切都很顺利，直到我陷入了如何将日期从文本字段获取到我的文本区域的问题。我尝试使用字符串字段 n 存储使用 toString() 方法分配给它的 LocalDate 对象，但它一直返回为 null。

代码如下：

public class FNAFrame extends JFrame {

public FNAFrame()
{
    super ("FNA Comments Generator");
    setLayout(new BorderLayout());

    setResizable(false);
    TextFrame comps = new TextFrame();
    add(comps);
    pack();
    setVisible(true);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

public static void main(String[] args) {

    SwingUtilities.invokeLater(new Runnable() {
        @Override
        public void run() {
            try {
                UIManager.setLookAndFeel("javax.swing.plaf.nimbus.NimbusLookAndFeel");
                // 
            } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) 
            {
                ex.printStackTrace();
            }


            new FNAFrame();

        }
    });
 }  
} // end of class FNA Frame


public class TextFrame extends JPanel {
// variable declarations
private JLabel newbLabel;

private JButton noChange_Button;

private JTextArea display_Area;

// end of variable declarations

public TextFrame()
{
    super(new GridBagLayout());

    setPreferredSize(new Dimension(300,200));
    setBackground(Color.white);

    init();  
  } // end of class constructor

    private void init()
    { 
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.insets = new Insets(10,10,10,10);

        // date picker
        DatePickin date_Picker = new DatePickin();
        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.BOTH;
        gbc.anchor = GridBagConstraints.EAST;
        add(date_Picker, gbc);

        // button to display date in textarea
        noChange_Button = new JButton("No Change");
        gbc.gridx = 0;
        gbc.gridy = 1;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.anchor = GridBagConstraints.WEST;
        add(noChange_Button, gbc);

        ///////////////////// TEXT AREA ///////////////////////

        display_Area = new JTextArea();
        gbc.gridx = 0;
        gbc.gridy = 3;
        //gbc.weighty = 1;
        gbc.gridwidth = 3;
        gbc.gridheight = 4;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.anchor = GridBagConstraints.SOUTHWEST;
        display_Area.setEditable(true);
        display_Area.setLineWrap(true);
        display_Area.setWrapStyleWord(true);

        JScrollPane scroll = new JScrollPane(display_Area);
        scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
        scroll.setPreferredSize(new Dimension(0, 70));
        add(scroll, gbc);

        // adding listeners to components
        // registering all components with their respective listeners
        CompHandler compHandler = new CompHandler();
        noChange_Button.addActionListener(compHandler);
    }

    // class to handle text fields
    private class CompHandler implements ActionListener
    {
        DatePickin date = new DatePickin();

        private String newbDate;

        @Override
        public void actionPerformed(ActionEvent e)  
        {
            Object button_command = e.getActionCommand();

            try {

                if (button_command.equals("No Change"))
                {    
                    newbDate = date.strDate;

                    display_Area.setText("The date is " + newbDate);
                    display_Area.setFont(new Font("Serif", Font.BOLD, 18));
                    display_Area.setForeground(Color.black);
                }
            }
            catch (NullPointerException np)
            {
            }       
        }
       } // end component handler class 
} // end of TextFrame class


public class DatePickin extends javafx.embed.swing.JFXPanel{

private DatePicker date_Picker;
String strDate;
private VBox pane;

public DatePickin()
{
    setLayout(new FlowLayout());
    setPreferredSize(new Dimension(90, 30));

    init();   
} // end of class constructor

private void init()
{
    pane = new VBox();
    pane.setBackground(Background.EMPTY);
    pane.setAlignment(Pos.CENTER_LEFT);
    getDate();
    pane.getChildren().addAll(date_Picker);

    Platform.runLater(this::createScene);
}

public void getDate()
{
    date_Picker = new DatePicker();

    date_Picker.setShowWeekNumbers(false);

    date_Picker.setOnAction((e) -> {

        LocalDate ld;
        try
        {
            //This is where i the problem is
            ld = date_Picker.getValue();

            strDate = ld.toString();
        }
        catch(UnsupportedOperationException uoe)
        {
        }
    });
}

private void createScene()
{
    Scene scene = new Scene(pane);
    setScene(scene);
}

}

Answer 1

有很多问题，但您的第一个问题是在 CompHandler

中创建 DatePickin 的新实例

private class CompHandler implements ActionListener
{
    DatePickin date = new DatePickin();

这与屏幕上的 DatePickin 实例无关，因此它将始终是 null。

相反，您应该将 DatePickin 的引用传递给 CompHandler

private class CompHandler implements ActionListener {

    private DatePickin pickin;

    public CompHandler(DatePickin pickin) {
        this.pickin = pickin;
    }

接下来，我不会获得 LocalDate 的 String 表示，您应该根据需要获得对 LocalDate 和格式的引用。您还应该限制人们访问您的 class 字段并转而支持 getter

public class DatePickin extends javafx.embed.swing.JFXPanel {

    private DatePicker date_Picker;
    private LocalDate dateValue;
    //...

    public void getDate() {
        date_Picker = new DatePicker();
        date_Picker.setShowWeekNumbers(false);
        date_Picker.setOnAction((e) -> {

            try {
                dateValue = date_Picker.getValue();
            } catch (UnsupportedOperationException uoe) {
                uoe.printStackTrace();
            }
        });
    }

    public LocalDate getDateValue() {
        return dateValue;
    }

然后，当 No Change 按钮被点击时，您可以直接获取 LocalDate 的值并随意使用它...

if (button_command.equals("No Change")) {
    LocalDate newbDate = pickin.getDateValue();

    display_Area.setText("The date is " + newbDate);
    display_Area.setFont(new Font("Serif", Font.BOLD, 18));
    display_Area.setForeground(Color.black);
}

Answer 2

好吧，我想通了..我按照 madpro 的建议做了，但是 FNAComponents class 内的 CompHandler class 声明中有一个错误，在那里我将 Jcomponents 初始化为它们各自的动作侦听器...

这是我所做的

private void init()
{ 
    GridBagConstraints gbc = new GridBagConstraints();
    gbc.insets = new Insets(10,10,10,10);

    // date picker
    DatePickin date_Picker = new DatePickin(); /// here i used the same object i created here in the CompHandler class as the arg
    gbc.gridx = 0;
    gbc.gridy = 0;
    gbc.fill = GridBagConstraints.BOTH;
    gbc.anchor = GridBagConstraints.EAST;
    add(date_Picker, gbc);

    // button to display date in textarea
    noChange_Button = new JButton("No Change");
    gbc.gridx = 0;
    gbc.gridy = 1;
    gbc.fill = GridBagConstraints.HORIZONTAL;
    gbc.anchor = GridBagConstraints.WEST;
    add(noChange_Button, gbc);

    ///////////////////// TEXT AREA ///////////////////////

    display_Area = new JTextArea();
    gbc.gridx = 0;
    gbc.gridy = 3;
    //gbc.weighty = 1;
    gbc.gridwidth = 3;
    gbc.gridheight = 4;
    gbc.fill = GridBagConstraints.HORIZONTAL;
    gbc.anchor = GridBagConstraints.SOUTHWEST;
    display_Area.setEditable(true);
    display_Area.setLineWrap(true);
    display_Area.setWrapStyleWord(true);

    JScrollPane scroll = new JScrollPane(display_Area);
    scroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
    scroll.setPreferredSize(new Dimension(0, 70));
    add(scroll, gbc);

    // adding listeners to components
    // registering all components with their respective listeners
    CompHandler compHandler = new CompHandler(date_Picker); // here u can see i added the reference of DatePicker to the class as an arg
    noChange_Button.addActionListener(compHandler);
}

我创建了一个对象 date_Picker 以在 init 方法中将面板放置在我的 swing 中。我将同一个对象用作 CompHandler class 的参数。感谢 madpro 的指导

当我在 DatePicker 中选择日期时如何获取文本字段值

how to get the textfield value when i choose a date in DatePicker

java

swing

javafx

datepicker