SWING(Menu Layout)

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


/* MenuLayoutDemo.java requires no other files. */

public class MenuLayoutDemo {
public JMenuBar createMenuBar() {
JMenuBar menuBar = new JMenuBar();
menuBar.setLayout(new BoxLayout(menuBar, BoxLayout.PAGE_AXIS));
menuBar.add(createMenu("Menu 1"));
menuBar.add(createMenu("Menu 2"));
menuBar.add(createMenu("Menu 3"));

menuBar.setBorder(BorderFactory.createMatteBorder(0,0,0,1,
Color.BLACK));
return menuBar;
}

// used by createMenuBar
public JMenu createMenu(String title) {
JMenu m = new HorizontalMenu(title);
m.add("Menu item #1 in " + title);
m.add("Menu item #2 in " + title);
m.add("Menu item #3 in " + title);

JMenu submenu = new HorizontalMenu("Submenu");
submenu.add("Submenu item #1");
submenu.add("Submenu item #2");
m.add(submenu);

return m;
}

/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("MenuLayoutDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

//Create and set up the content pane.
MenuLayoutDemo demo = new MenuLayoutDemo();
Container contentPane = frame.getContentPane();
contentPane.setBackground(Color.WHITE); //contrasting bg
contentPane.add(demo.createMenuBar(),
BorderLayout.LINE_START);

//Display the window.
frame.setSize(300, 150);
frame.setVisible(true);
}

public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application~s GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}

class HorizontalMenu extends JMenu {
HorizontalMenu(String label) {
super(label);
JPopupMenu pm = getPopupMenu();
pm.setLayout(new BoxLayout(pm, BoxLayout.LINE_AXIS));
}

public Dimension getMinimumSize() {
return getPreferredSize();
}

public Dimension getMaximumSize() {
return getPreferredSize();
}

public void setPopupMenuVisible(boolean b) {
boolean isVisible = isPopupMenuVisible();
if (b != isVisible) {
if ((b==true) && isShowing()) {
//Set location of popupMenu (pulldown or pullright).
//Perhaps this should be dictated by L&F.
int x = 0;
int y = 0;
Container parent = getParent();
if (parent instanceof JPopupMenu) {
x = 0;
y = getHeight();
} else {
x = getWidth();
y = 0;
}
getPopupMenu().show(this, x, y);
} else {
getPopupMenu().setVisible(false);
}
}
}
}
}