Creating Windows - Beginning Java - page 885

This creates a menu item as a JMenuItem object with the label "New" , adds it to the menu represented by
the fileMenu object, and returns a reference to the menu item. You need the reference to the menu item to
enable the program to react to the user clicking the item.
You can also create the JMenuItem object explicitly and use another version of the add() method for the
JMenu object to add it:
JMenuItem newMenu = new JMenuItem("New"); // Create the item
fileMenu.add(newMenu); // and add it to the menu

You can operate on menu items by using the following JMenuItem class methods:
• void setEnabled(boolean b) : If b has the value true , the menu item is enabled; false makes
it. The default state is enabled.
• void setText(String label) : Sets the menu item label to the string stored in the label.
• String getText() : Returns the current menu item label.
Because the JMenu class is a subclass of JMenuItem , these methods also apply to JMenu objects.
To add a separator to a menu you call the addSeparator() method for the JMenu object. The separator
appears following the previous menu item that you added to the menu.
Let's now create the drop-down menus for the File and Element menus on the menu bar in the Sketcher
application and try out some of the menu items.

TRY IT OUT: Adding Drop-Down Menus
You can change the definition of our SketcherFrame class to do this:

// Frame for the Sketcher application
import javax.swing.*;

public class SketcherFrame extends JFrame {
// Constructor
public SketcherFrame(String title) {
setTitle(title); // Set the window
title
setDefaultCloseOperation(EXIT_ON_CLOSE);

setJMenuBar(menuBar); // Add the menu bar
to the window

JMenu fileMenu = new JMenu("File"); // Create File menu
JMenu elementMenu = new JMenu("Elements"); // Create Elements

menu

// Construct the file drop-down menu
newItem = fileMenu.add("New"); // Add New item

openItem = fileMenu.add("Open"); // Add Open item

closeItem = fileMenu.add("Close"); // Add Close item