The JMenu class represents the anchored menus attached to a JMenuBar or another JMenu. Menus directly attached to a menu bar are called top-level menus. Submenus, on the other hand, are not attached to a menu bar but to a menu item that serves as its title. This menu item title is typically marked by a right arrow, indicating that its menu appears alongside the menu item if the user selects it.

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

public class MenuExample extends JPanel {

	public JTextPane pane;
	public JMenuBar menuBar;

	public MenuExample() {
		menuBar = new JMenuBar();
		JMenu formatMenu = new JMenu("Justify");
		formatMenu.setMnemonic('J');

		MenuAction leftJustifyAction = 
new MenuAction("Left", new ImageIcon("left.gif"));
		MenuAction rightJustifyAction = 
new MenuAction("Right", new ImageIcon("right.gif"));
		MenuAction centerJustifyAction = 
new MenuAction("Center", new ImageIcon("center.gif"));
		MenuAction fullJustifyAction = 
new MenuAction("Full", new ImageIcon("full.gif"));

		JMenuItem item;
		item = formatMenu.add(leftJustifyAction);
		item.setMnemonic('L');
		item = formatMenu.add(rightJustifyAction);
		item.setMnemonic('R');
		item = formatMenu.add(centerJustifyAction);
		item.setMnemonic('C');
		item = formatMenu.add(fullJustifyAction);
		item.setMnemonic('F');

		menuBar.add(formatMenu);
		menuBar.setBorder(new BevelBorder(BevelBorder.RAISED));

	}

	class MenuAction extends AbstractAction {

		public MenuAction(String text, Icon icon) {
			super(text, icon);
		}

		public void actionPerformed(ActionEvent e) {
			try {
				pane.getStyledDocument().insertString(0, "Action [" + 
e.getActionCommand() + "] performed!\n", null);
			} catch (Exception ex) {
				ex.printStackTrace();
			}
		}
	}

	public static void main(String s[]) {

		MenuExample example = new MenuExample();
		example.pane = new JTextPane();
		example.pane.setPreferredSize(new Dimension(250, 250));
		example.pane.setBorder(new BevelBorder(BevelBorder.LOWERED));

		JFrame frame = new JFrame("Menu Example");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setJMenuBar(example.menuBar);
		frame.getContentPane().add(example.pane, BorderLayout.CENTER);
		frame.pack();
		frame.setVisible(true);
	}
}