Re: Java Threads Question

import javax.swing.*;
import java.awt.GridLayout;
import javax.swing.AbstractAction;
import java.awt.event.*;
import java.util.concurrent.locks.ReentrantLock;

class JPasswordDialog extends JDialog
{
    Mediator mediator=null;

    JPanel mainPanel=null;
    JPanel usernamePanel=null;
    JPanel passwordPanel=null;
    JPanel buttonPanel=null;
    JLabel usernameL=null;
    JLabel passwordL=null;
    JTextField usernameTF=null;
    JPasswordField passwordTF=null;
    JButton login=null;
    JButton cancel=null;

    PasswordDialogOKAction passwordDialogOKAction=null;

    public JPasswordDialog(JFrame owner, String title, Mediator m)
    {
        super(owner, title);
        this.mediator=m;

        instantiateComponents();
        initMainPanel();
        initUsernamePanel();
        initPasswordPanel();
        initButtonPanel();
        this.add(mainPanel);

        setResizable(false);
        setBounds(owner.getX()+owner.getWidth()/2-125,
owner.getY()+owner.getHeight()/2-65,250,130);
    }

    public String[] prompt()
    {
        setVisible(true);

        try
        {
            synchronized (passwordDialogOKAction.lock)
            {
                wait();
            }
        }
        catch(Exception e)
        {
            System.err.println(e);
        }

        return new String[]{getUsername(),getPassword()};
    }

    public JTextField getUsernameTextField()
    {
        return usernameTF;
    }

    public JTextField getPasswordField()
    {
        return passwordTF;
    }

    public synchronized String getUsername()
    {
        return usernameTF.getText();
    }

    public synchronized String getPassword()
    {
        return new String(passwordTF.getPassword());
    }

    private void instantiateComponents()
    {
        mainPanel=new JPanel();
        usernamePanel=new JPanel();
        passwordPanel=new JPanel();
        buttonPanel=new JPanel();
        usernameL=new JLabel("Username: ");
        passwordL=new JLabel("Password: ");
        usernameTF=new JTextField();
        passwordTF=new JPasswordField();
        login=new JButton("Login");
        cancel=new JButton("Cancel");
    }

    private void initMainPanel()
    {
        mainPanel.setLayout(new GridLayout(3,1,0,0));
        mainPanel.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));
        mainPanel.add(usernamePanel);
        mainPanel.add(passwordPanel);
        mainPanel.add(buttonPanel);
    }

    private void initUsernamePanel()
    {
        usernamePanel.setLayout(null);
        usernameL.setBounds(0,0,70,20);
        usernameTF.setBounds(80,0,145,20);
        usernamePanel.add(usernameL);
        usernamePanel.add(usernameTF);
    }

    private void initPasswordPanel()
    {
        passwordPanel.setLayout(null);
        passwordL.setBounds(0,0,70,20);
        passwordTF.setBounds(80,0,145,20);
        passwordPanel.add(passwordL);
        passwordPanel.add(passwordTF);
    }

    private void initButtonPanel()
    {
        buttonPanel.setLayout(new GridLayout(1,2,15,15));
        buttonPanel.add(login);
        buttonPanel.add(cancel);
        login.setAction((passwordDialogOKAction=new
PasswordDialogOKAction("Login",this, mediator)));
        cancel.setAction(new PasswordDialogCancelAction("Cancel",this));
    }
}

class PasswordDialogOKAction extends AbstractAction
{
    Mediator mediator=null;
    JPasswordDialog dialog=null;

    public ReentrantLock lock=new ReentrantLock();

    public PasswordDialogOKAction(String name, JPasswordDialog dialog,
Mediator m)
    {
        super(name);
        this.dialog=dialog;
        this.mediator=m;
        lock.lock();
    }

    public void actionPerformed(ActionEvent ae)
    {
        if(dialog.getUsername().length()<0 ||
dialog.getUsername().length()>20)
        {
            JOptionPane.showMessageDialog(dialog, "Invalid Username.");
            lock.unlock();
            return;
        }

        if(dialog.getPassword().length()<0 ||
dialog.getPassword().length()>20)
        {
            JOptionPane.showMessageDialog(dialog, "Invalid Password.");
            lock.unlock();
            return;
        }

        dialog.dispose();
    }
}

class PasswordDialogCancelAction extends AbstractAction
{
    JPasswordDialog dialog=null;

    public PasswordDialogCancelAction(String name, JPasswordDialog dialog)
    {
        super(name);
        this.dialog=dialog;
    }

    public void actionPerformed(ActionEvent ae)
    {
        dialog.dispose();
    }
}

See the prompt method for the idea...

Mearvk