JFrame ActionListener

[grako84]

Hi folks!
I'm trying to wire simple code and so far I'm stuck on ActionListener.
My program should contain (JMenu) Menu called SELECT and two options InnerFrame 1 and InnerFrame 2. To debug it I've started using System.EXIT , unfortunately I cant compile my program, I'm receiving an error: "java:48: non-static method addActionListener(java.awt.event.ActionListener) cannot be referenced from a static context
JMenuItem.addActionListener(this);"

code goes here

import javax.swing.JInternalFrame;
import javax.swing.JDesktopPane;
import javax.swing.JMenu;
import javax.swing.JMenuItem;
import javax.swing.JMenuBar;
import javax.swing.JFrame;
import javax.swing.KeyStroke;

import java.awt.event.*;
import java.awt.*;

/*
 * InternalFrameDemo.java
 *
 */

public class InternalFrameDemo1 extends JFrame implements ActionListener{



    public InternalFrameDemo1() {

        super("My First Internal Frame");


		int inset = 10;
        Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
        setBounds(inset, inset,
                  screenSize.width  - inset*2,
                  screenSize.height - inset*2);

		//Set up the GUI.
        JDesktopPane desktop = new JDesktopPane(); //a specialized layered pane
        JInternalFrame innerframe = new JInternalFrame("Internal Window" ,
              										false, //resizable
              										false, //closable
              										true, //maximizable
              										false);//iconifiable


	JMenuBar mb = new JMenuBar();

	JMenu helpMenu = new JMenu("Select", true);


helpMenu.add(new JMenuItem ("Exit"));

JMenuItem.addActionListener(this);

	mb.add(helpMenu);
	setJMenuBar(mb);
	innerframe.setSize(640,480);
		innerframe.setVisible(true); //necessary as of 1.3
       desktop.add(innerframe);

        setContentPane(desktop); //important as it allows us to add items to the desktop
        setSize(640,480);
        setVisible(true);
		//setResizable(false);
    }


    public static void main(String[] args) {

        InternalFrameDemo1 frame = new InternalFrameDemo1();

    }
public void actionPerformed(ActionEvent e)
{

String message = "";
if (e.getSource() instanceof JMenuItem){
if (e.getActionCommand().equals("Exit")) //message = "The New Item was selected";

System.exit(0);
//JOptionPane.showMessageDialog(null,message, "The Menu was clicked", JOptionPane.PLAIN_MESSAGE);
}
}
}

Could you advise, please?

Best regards
Thom