// -----------------------MenuExample.java--------------------------
   
import com.sun.java.swing.*; 
 public class MenuExample extends JFrame {
    public MenuExample() {
      JMenuBar mb = new JMenuBar();
      newMenu(mb);
      newMenu(mb);
      newMenu(mb);
      setJMenuBar(mb);
    }
    public void newMenu(JMenuBar mb) {
      JMenu m = (JMenu)mb.add(new JMenuPlus("File"));
      m.add("Menu item");
      m.add("Menu item");
      m.add("Menu item");
      JMenu m1 = (JMenu)m.add(new JMenuPlus("menu"));
     m1.add("Submenu item");
      m1.add("Submenu item");
    }
    public static void main(String args[]) {
      MenuExample f = new MenuExample();
      f.pack();
      f.show();
    }
 }
 
// --------------------------------------------------------------
// -------------------------JMenuPlus.java-----------------------
   /*
   *
   * Copyright 1998 by Sun Microsystems, Inc.,
   * 901 San Antonio Road, Palo Alto, California, 94303, U.S.A.
   * All rights reserved.
   *
   * This software is the confidential and proprietary information
   * of Sun Microsystems, Inc. ("Confidential Information"). You
   * shall not disclose such Confidential Information and shall use
   * it only in accordance with the terms of the license agreement
   * you entered into with Sun.
   */
 import com.sun.java.swing.*;
 import java.awt.*;
 /**
   * A subclass of JMenu which adds a simple heuristic for ensuring
   * that the popup menu gets placed onscreen.
   */
   public class JMenuPlus extends JMenu {
      public JMenuPlus(String label) {
         super(label);
      }
   
      /**
      * Override the implementation in JMenu in order to be more
      * intelligent about determining the placement of the popup menu.
      *
      * @param b a boolean value -- true to make the menu visible,
      * false to hide it
      */
   
      public void setPopupMenuVisible(boolean b) {
         boolean isVisible = isPopupMenuVisible();
         if (b != isVisible) {
            // Set location of popupMenu (pulldown or pullright)
            // Perhaps this should be dictated by L&F
            if ((b==true) && isShowing()) {
               Point p = getPopupMenuOrigin();
               getPopupMenu().show(this, p.x, p.y);
            } else {
               getPopupMenu().setVisible(false);
            }
         } 
      }
   
      /**
      * Override the implementation in JMenu in order to be more
      * intelligent about determining the placement of the popup menu.
      *
      * @returns a Point in the coordinate space of the menu instance
      * which should be used as the origin of the JMenu's popup menu.
      */
      protected Point getPopupMenuOrigin() {
         int x = 0;
         int y = 0;
         JPopupMenu pm = getPopupMenu();
         // Figure out the sizes needed to caclulate the menu position
         Dimension screenSize =Toolkit.getDefaultToolkit().getScreenSize();
         Dimension s = getSize();
         Dimension pmSize = pm.getSize();
         // For the first time the menu is popped up, 
         // the size has not yet been initiated
         if (pmSize.width==0) {
            pmSize = pm.getPreferredSize();
         }
         Point position = getLocationOnScreen();
   
         Container parent = getParent();
         if (parent instanceof JPopupMenu) {
            // We are a submenu (pull-right)
   
            // First determine x:
            if (position.x+s.width + pmSize.width < screenSize.width) {
               x = s.width; // Prefer placement to the right
            } else {
         x = 0-pmSize.width; // Otherwise place to the left
         }
         // Then the y:
         if (position.y+pmSize.height < screenSize.height) {
            y = 0; // Prefer dropping down
         } else {
            y = s.height-pmSize.height; // Otherwise drop 'up'
         }
      } else {
      // We are a toplevel menu (pull-down)
   
      // First determine the x:
      if (position.x+pmSize.width < screenSize.width) {
         x = 0; // Prefer extending to right 
      } else {
         x = s.width-pmSize.width; // Otherwise extend to left
      }
      // Then the y:
      if (position.y+s.height+pmSize.height < screenSize.height) {
         y = s.height; // Prefer dropping down
         } else {
            y = 0-pmSize.height; // Otherwise drop 'up'
         }   
      }
         return new Point(x,y);
      }
   }