how to check if user has input something or not in JDialogBox?

I have created a custom dialog box which requires 3 fields

public class Test{

    public static void main(String args[])

    {

        JTextField firstName = new JTextField();

        JTextField lastName = new JTextField();

        JPasswordField password = new JPasswordField();

        final JComponent[] inputs = new JComponent[] {

                        new JLabel("First"),

                        firstName,

                        new JLabel("Last"),

                        lastName,

                        new JLabel("Password"),

                        password

        };

        JOptionPane.showMessageDialog(null, inputs, "My custom dialog",JOptionPane.PLAIN_MESSAGE);

        System.out.println("You entered " +firstName.getText() + ", " +lastName.getText() + ", " +password.getText());

    }
}

How do I check if the user has inserted all fields or not? And even if user close the dialog box it display

You entered , ,

I want to check user input in field and close application if user close dialog box without dsplaying

"You entered , , "

Solution

You can check if user has inserted all fields or not as follows:

if(firstName.getText() != "" && lastName.getText() != "" && password.getText() != "")
    System.out.println("All fields have been filled!");
else
    System.out.println("Some fields are need to be filled!");

EDIT:

For displaying a message after closing the dialog box, you can do it like:

myframe.addWindowListener(new WindowAdapter()
{
    public void windowClosing(WindowEvent e)
    {
        JOptionPane.showMessageDialog(null,"You entered " + firstName.getText() + ", " + lastName.getText() + ", " +password.getText());
    }
});

EDIT2:

OK, I think I understand your question now, try this:

public class Test
{
    public static void main(String args[])
    {
        JTextField firstName = new JTextField();
        JTextField lastName = new JTextField();
        JPasswordField password = new JPasswordField();
        final JComponent[] inputs = new JComponent[]
        {
            new JLabel("First"),
            firstName,
            new JLabel("Last"),
            lastName,
            new JLabel("Password"),
            password        
        };
        int i = JOptionPane.showConfirmDialog(null, inputs, "My custom dialog",JOptionPane.PLAIN_MESSAGE);
        if(i == 0) System.out.println("You entered " + firstName.getText() + ", " + lastName.getText() + ", " + password.getText());
    }
}