This section describes 3 Swing classes, JMenuBar, JMenu, and JMenuItem, to build a menu interface for a frame window. A typical menu interface has a menu bar with multiple menus or menu items. A menu can have multiple sub menus or menu items.
javax.swing.JMenuBar - A Swing class representing the menu bar on the main frame.
javax.swing.JMenu objects added a JMenuBar object will be displayed horizontally.
Interesting methods of JMenuBar include:
JMenuBar() - Constructor to create a menu bar which can be added to a frame window.
add(JMenu) - Method to add a new JMenu object to the end of the menu be list.
getMenuCount() - Method to return the number of menus in this menu bar.
getMenu(int) - Method to return the JMenu object of the specified position index. Of course, index 0 is the first menu.
getSubElements() - Method to return an array of MenuElement objects.
isSelected() - Method to return true if an element is currently selected in the menu bar.
javax.swing.JMenu - A Swing class representing a user interface menu.
A JMenu object can be added to a JMenuBar or another JMenu object to form a menu tree structure.
A JMenu object actually has two graphical components, a clickable button displayed in the parent JMenu or JMenuBar
and a popup window. When its button is clicked, its pop up window will be displayed.
Interesting methods of JMenu include:
JMenu(String) - Constructor to create a menu with the specified string as its button text.
add(JMenuItem) - Method to add a JMenuItem object to the end of its current menu item list.
addSeparator() - Method to add a menu separator to the end of its current menu item list.
getItemCount() - Method to return the number of its menu items.
getItem(int pos) - Method to return the JMenuItem object of the specified position index. Of course, index 0 is the first menu item.
isSelected() - Method to return true if this menu is selected.
isTopLevelMenu() - Method to return true if this menu is a top menu. A top menu is a menu added to the menu bar, not to another menu.
doClick(int) - Method to simulate a user click on this menu.
javax.swing.JMenuItem - A Swing class representing a user interface menu item.
A JMenuItem object can be added to a JMenuBar or another JMenu object in a menu tree structure.
A JMenuItem should be associated with a MenuKeyListener object so that tasks can be performed with the menu item is clicked.
Interesting methods of JMenuItem include:
JMenuItem(String) - Constructor to create a menu item with the specified string as its button text.
addMenuKeyListener(MenuKeyListener) - Method to add a MenuKeyListener object to this menu item.
setEnabled(boolean) - Method to set this menu item to be enabled or disabled based on the specified Boolean value.
