Create JMenuItem from Action in Java

//from   w ww . j  a  va2s .co m
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;

class ShowAction extends AbstractAction {
  Component parentComponent;

  public ShowAction(Component parentComponent) {
    super("About");
    putValue(Action.MNEMONIC_KEY, new Integer(KeyEvent.VK_A));
    this.parentComponent = parentComponent;
  }

  public void actionPerformed(ActionEvent actionEvent) {
    Runnable runnable = new Runnable() {
      public void run() {
        JOptionPane.showMessageDialog(parentComponent, "About Swing", "About Box V2.0",
            JOptionPane.INFORMATION_MESSAGE);
      }
    };
    EventQueue.invokeLater(runnable);
  }
}

public class Main {
  public static void main(final String args[]) {
    JFrame frame = new JFrame("MenuSample Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JMenuBar menuBar = new JMenuBar();

    // File Menu, F - Mnemonic
    JMenu fileMenu = new JMenu("File");
    fileMenu.setMnemonic(KeyEvent.VK_F);
    menuBar.add(fileMenu);

    // File->New, N - Mnemonic
    JMenuItem newMenuItem = new JMenuItem(new ShowAction(frame));
    fileMenu.add(newMenuItem);

    frame.setJMenuBar(menuBar);
    frame.setSize(350, 250);
    frame.setVisible(true);
  }
}