Problem with actionperformed callback

I tried to create function, what shows textdialog, when client press the buton, but the problem is that i have defined frame under public static void main and in ActionPerformed callback first parameter "frame" is undefined. How could i fix this?

import java.awt.*;







import java.awt.event.*;







import java.applet.Applet;







import javax.swing.*;

public class Vestlus extends Applet implements ActionListener {







TextField tf = new TextField("");







Button nupp = new Button(" Sisesta ");

public Vestlus()







{







add(tf);







add(nupp);







nupp.addActionListener(this);

}







public void actionPerformed(ActionEvent e)







{







if(e.getSource() == nupp)







{







JOptionPane.showMessageDialog(frame,"Hoiatus","Vää rtused ei klapi!", JOptionPane.INFORMATION_MESSAGE);

}







}







public static void main(String args[])







{

JFrame frame = new JFrame("Project LA");







frame.add(new Vestlus());







frame.setSize(300,200);







frame.setVisible(true);







frame.setDefaultCloseOperation(1);

}

}