Io ho il seguente codice, e mi domandavo come potevo integrare quello che mi hai consigliato con esso?

public class test extends JFrame implements EventListener{

private JDialog dialog;

public test(){

setTitle("test");
setBounds(100,100,420,300);

JMenuBar menuBar = MenuBar1();
JPanel northPanel = new JPanel();
JToolBar toolbar = ToolBar1();
northPanel.add(toolbar);

getContentPane().add(BorderLayout.NORTH,northPanel );

setJMenuBar(menuBar);

dialog = new JDialog(this,"",true);
dialog.setBounds(300,100,250,150);
dialog.getContentPane().setLayout(new BorderLayout());
dialog.setDefaultCloseOperation(JFrame.HIDE_ON_CLO SE);

setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}

class voceJmenuBar implements ActionListener {
public void actionPerformed(ActionEvent e) {

JPanel northPanel = new JPanel();
provaField = new JTextField(2);

northPanel.add(provaField);
northPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

dialog.getContentPane().add(BorderLayout.NORTH,nor thPanel);

dialog.setVisible(true);
}
}