Java JMenu add Mnemonic key

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;   
    /*from w ww  . ja  v  a  2 s .c om*/
public class Main implements ActionListener { 
  public Main () {   
    // Create a new JFrame container.   
    JFrame jfrm = new JFrame("Menu Demo"); 
   
    // Specify FlowLayout for the layout manager.   
    jfrm.setLayout(new FlowLayout());   
   
    // Give the frame an initial size.   
    jfrm.setSize(220, 200);   
   
    // Terminate the program when the user closes the application.   
    jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);   
 
    // Create the menu bar. 
    JMenuBar jmb = new JMenuBar(); 
 
    // Create the File menu. 
    JMenu jmFile = new JMenu("File");
    jmFile.setMnemonic(KeyEvent.VK_F); 
    
    JMenuItem jmiOpen = new JMenuItem("Open"); 
    
    jmiOpen.setAccelerator( 
          KeyStroke.getKeyStroke(KeyEvent.VK_O, 
                                 InputEvent.CTRL_DOWN_MASK)); 
    
    JMenuItem jmiClose = new JMenuItem("Close"); 
    JMenuItem jmiSave = new JMenuItem("Save"); 
    JMenuItem jmiExit = new JMenuItem("Exit"); 
    jmFile.add(jmiOpen); 
    jmFile.add(jmiClose); 
    jmFile.add(jmiSave); 
    jmFile.addSeparator(); 
    jmFile.add(jmiExit); 
    jmb.add(jmFile); 
 
    // Create the Help menu. 
    JMenu jmHelp = new JMenu("Help"); 
    JMenuItem jmiAbout = new JMenuItem("About"); 
    jmHelp.add(jmiAbout); 
    jmb.add(jmHelp);  
 
    // Add action listeners for the menu items. 
    jmiOpen.addActionListener(this); 
    jmiClose.addActionListener(this); 
    jmiSave.addActionListener(this); 
    jmiExit.addActionListener(this); 
    jmiAbout.addActionListener(this); 
 
    // Add the menu bar to the frame. 
    jfrm.setJMenuBar(jmb);    
   
    // Display the frame.   
    jfrm.setVisible(true);   
  }   
 
  // Handle menu item action events. 
  public void actionPerformed(ActionEvent ae) {  
    // Get the action command from the menu selection. 
    String comStr = ae.getActionCommand(); 
 
    // If user chooses Exit, then exit the program. 
    if(comStr.equals("Exit")) System.exit(0); 
 
    // Otherwise, display the selection. 
    System.out.println(comStr + " Selected"); 
  }  
    
  public static void main(String args[]) {   
    // Create the frame on the event dispatching thread.   
    SwingUtilities.invokeLater(new Runnable() {   
      public void run() {   
        new Main();   
      }   
    });   
  }   
}