Java“JTextField.requestFocus()”在 JOptionPane 中不起作用

Question

我试图请求关注第一个用户名字段，但它没有关注文本字段。这是我的代码：

JTextField username = new JTextField();
JTextField password = new JPasswordField();
JTextField prefix = new JTextField();
username.requestFocus();
Object[] message = {
    "Username:", username,
    "Password:", password,
    "Prefix:", prefix
};

int option = JOptionPane.showConfirmDialog(null, message, "Login", JOptionPane.OK_CANCEL_OPTION);
username.requestFocus();
if (option == JOptionPane.OK_OPTION) {
    return ls.login(username.getText(), password.getText(), prefix.getText());
} else {
    return false;
}

如何请求用户名文本字段的焦点？

Answer 1

这里是怎么做的：

final JTextField username = new JTextField();
JTextField password = new JPasswordField();
JTextField prefix = new JTextField();
JPanel gridLayout = new JPanel(new GridLayout(6, 1));
gridLayout.add(new JLabel("Username:"));
gridLayout.add(username);
gridLayout.add(new JLabel("Password:"));
gridLayout.add(password);
gridLayout.add(new JLabel("Prefix:"));
gridLayout.add(prefix);

username.addAncestorListener(new AncestorListener() {
    @Override
    public void ancestorRemoved(AncestorEvent pEvent) {
    }

    @Override
    public void ancestorMoved(AncestorEvent pEvent) {
    }

    @Override
    public void ancestorAdded(AncestorEvent pEvent) {
        // TextField is added to its parent => request focus in Event Dispatch Thread
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                username.requestFocusInWindow();
            }
        });
    }
});

int option = JOptionPane.showConfirmDialog(null, gridLayout, "Login",
    JOptionPane.OK_CANCEL_OPTION);

我只是将您的Object[] message 替换为JPanel 对象，并使用AncestorListener 在将文本字段添加到其父级时收到通知。

注意：我不知道为什么它不适用于您的 Object[] message。