How can I give this password field focus?

问题

This may seem trivial, but I can't figure out how to give the password box in this dialog focus.

import javax.swing.JOptionPane;
import javax.swing.JPasswordField;

public class PasswordBox {
    @SuppressWarnings("unused")
    public String prompt() {
        JPasswordField pass = new JPasswordField(10);
        int action = JOptionPane.showConfirmDialog(null, pass,"Enter Password",JOptionPane.OK_CANCEL_OPTION); 
        return new String(pass.getPassword());
    }
}

I invoke it from other classes like this: String tmpPASS = new PasswordBox().prompt();

For some reason, when the dialog shows up, the "OK" button gets focus.

stacktrace (see Eng.Fouad's answer):

at javax.swing.JComponent.addNotify(Unknown Source)
at PasswordBox$1.addNotify(PasswordBox.java:14)
at java.awt.Container.addNotify(Unknown Source)

回答1:

Check out the solution presented in Dialog Focus.

Edit:

Using the approach suggested by Eng Fouad I believe the code should be:

JPasswordField pass = new JPasswordField(10)         
{
    public void addNotify()             
    {                 
        super.addNotify();
        requestFocusInWindow();             
    }         
};

Edit2:

The link in the "Dialog Focus" blog entry has a comment with a suggestion that works on Linux.

回答2:

import javax.swing.JOptionPane;
import javax.swing.JPasswordField;

public JOptionPane pane;

public class PasswordBox
{
    @SuppressWarnings("unused")
    public String prompt()
    {
        pane = new JOptionPane();
        JPasswordField pass = new JPasswordField(10)
        {
            public void addNotify()
            {
                pane.addNotify();
                requestFocus();
            }
        };
        int action = pane.showConfirmDialog(null, pass,"Enter Password",JOptionPane.OK_CANCEL_OPTION);
        return new String(pass.getPassword());
     }
}

or here is another way to do it:

JPanel panel = new JPanel();
JPasswordField pass = new JPasswordField(10)
{
    public void addNotify()
    {
        panel.addNotify();
        requestFocus();
    }
};
panel.add(pass);
JOptionPane pane = new JOptionPane();
JButton btnOK = new JButton("OK");
JButton btnCancel = new JButton("Cancel");
Object[] options = {btnOK, btnCancel};
pane.showOptionDialog(null, panel, "Enter the password", JOptionPane.DEFAULT_OPTION, JOptionPane.PLAIN_MESSAGE, null, options, null);

Edit (by camickr, feel free to remove if this is not correct). I believe the code should be:

JPasswordField pass = new JPasswordField(10)         
{
    public void addNotify()             
    {                 
        super.addNotify();
        requestFocusInWindow();             
    }         
};

回答3:

The problem is that JOptionPane is completely self contained, and seems to offer no way to specify which GUI component gets the initial focus. One solution would be to write your own subclass of Dialog - that will let you control the layout exactly and set the focus appropriately.

You might also try a javax.swing.SwingWorker. You could create one of these and start it BEFORE showing the password dialog. In the doInBackground() method, sleep for a short time, in the done() method use SwingUtilties.invokeLater() and within that Runnable, issue pass.requestFocusInWindow().