System.setProperty("apple.laf.useScreenMenuBar", "true") : System Properties « Development « Java Tutorial

1. Java Tutorial
2. Development
3. System Properties

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;

public class Main {

  static {
    System.setProperty("apple.laf.useScreenMenuBar", "true");
  }

  public static void main(String[] args) {
    JFrame frame = new JFrame("Menu Bar Demo");
    JMenuBar bar = new JMenuBar();
    JMenu fileMenu = new JMenu("File");
    JMenu editMenu = new JMenu("Edit");
    JMenu helpMenu = new JMenu("Help");
    bar.add(fileMenu);
    bar.add(editMenu);
    bar.add(helpMenu);
    frame.setSize(300, 150);
    frame.setJMenuBar(bar);
    frame.setVisible(true);
  }

}