java - JDateChooser focusListener

我正在尝试向JDateChooser添加focusListener，以便当用户选择dateOfBirth时，当焦点丢失时，它将在文本字段上显示年龄。但这不起作用
这就是我尝试过的方式

导入java.awt.BorderLayout;

public class agecalc extends JFrame {
    private JTextField age;
    private JDateChooser dOB;
    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    agecalc frame = new agecalc();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    /**
     * Create the frame.
     */
    public agecalc() {

        JPanel panel = new JPanel();
        GroupLayout groupLayout = new GroupLayout(getContentPane());
        groupLayout.setHorizontalGroup(
            groupLayout.createParallelGroup(Alignment.LEADING)
                .addGroup(groupLayout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(panel, GroupLayout.PREFERRED_SIZE, 290, GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(134, Short.MAX_VALUE))
        );
        groupLayout.setVerticalGroup(
            groupLayout.createParallelGroup(Alignment.LEADING)
                .addGroup(groupLayout.createSequentialGroup()
                    .addGap(20)
                    .addComponent(panel, GroupLayout.PREFERRED_SIZE, 195, GroupLayout.PREFERRED_SIZE)
                    .addContainerGap(47, Short.MAX_VALUE))
        );
        panel.setLayout(null);

        dOB = new JDateChooser();
        dOB.setBounds(97, 52, 95, 20);
        panel.add(dOB);

        age = new JTextField();
        age.setBounds(97, 83, 86, 20);
        panel.add(age);
        age.setColumns(10);
        getContentPane().setLayout(groupLayout);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 450, 300);

                    AGECalc ageCalc=new AGECalc();

        dOB.addFocusListener(ageCalc);
    }
    private class AGECalc implements FocusListener{

        @Override
        public void focusGained(FocusEvent e) {

        }

        @Override
        public void focusLost(FocusEvent e) {
            // TODO Auto-generated method stub
            Calendar fromDate;
               Calendar toDate;
               Date dateOfBirth= dOB.getDate();
               Date now = new Date();
               fromDate=Calendar.getInstance();
               toDate=Calendar.getInstance();

                   fromDate.setTime(dateOfBirth);
                   toDate.setTime(now);
                   int ageYear = toDate.get(Calendar.YEAR) - (fromDate.get(Calendar.YEAR) );
                   age.setText(Integer.toString(ageYear));
                   System.out.println(ageYear);



            }
        }






    public JTextField getAge() {
        return age;
    }

    public void setAge(JTextField age) {
        this.age = age;
    }

    public JDateChooser getdOB() {
        return dOB;
    }

    public void setdOB(JDateChooser dOB) {
        this.dOB = dOB;
    }
}

最佳答案

我正在尝试将focusListener添加到JDateChooser，以便当
用户选择dateOfBirth时，当
失去焦点。


与其相反，我建议您实现PropertyChangeListener并将其附加到日期选择器。这样，每次用户通过选择日期或通过手动输入新日期来更新所选值时，都会更新文本字段，而不考虑日期选择器是否失去焦点。

例如：

final JTextField ageTextField = new JTextField(20);
ageTextField.setEditable(false);

JDateChooser dateChooser = new JDateChooser(new Date());
dateChooser.addPropertyChangeListener("date", new PropertyChangeListener() {
    @Override
    public void propertyChange(PropertyChangeEvent evt) {
        Calendar dateofBirth = Calendar.getInstance();
        dateofBirth.setTime((Date)evt.getNewValue());

        Calendar today = Calendar.getInstance();
        int age = today.get(Calendar.YEAR) - dateofBirth.get(Calendar.YEAR);

        if(today.get(Calendar.MONTH) < dateofBirth.get(Calendar.MONTH) ||
          (today.get(Calendar.MONTH) == dateofBirth.get(Calendar.MONTH) && today.get(Calendar.DAY_OF_MONTH) < dateofBirth.get(Calendar.DAY_OF_MONTH))) {
            age--;
        }

        ageTextField.setText(String.valueOf(age));
    }
});

查看此问题的答案中的另一个示例：


Using JCalendar in a JDialog




题外话

关于此行（和其他类似的行）：

dOB.setBounds(97, 52, 95, 20);

在使用Swing时，强烈建议不要使用诸如setBounds()，setLocation()或setSize()之类的方法，因为这些方法会导致组件的确切位置。 Layout Managers负责处理组件的尺寸和位置。这些是要强调这一点的有趣主题：


Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?
Providing white space in a Swing GUI
Nested Layout approach