Menus

1
Menus

• Pull-downs and popups

2
Tooltips

• Tooltips
• a ToolTip is a context-sensitive text string that
  is displayed in a popup window when the mouse
  rests over a particular object on the screen
• JButton myButton new JButton(Accept Order)
• myButton.setToolTipText(By selecting this button
  you accept the order and it will be shipped to
  you)

3
Menus

• To create a Menu
• create a Menu Bar
• create a Menu Object
• create Menu Items
• add Menu Items to a Menu Object
• add Menu Objects to the Menu Bar

4
Menus

• Pull-downs are found on a Menu bar
• Menu bars may only appear in frames
• JMenuBar menuBar new JMenuBar()

5
Menus

• Create the Menu object
• JMenu hamburgerMenu new JMenu(Hamburger)
• Next create the Menu items
• JMenuItem plainItem new JMenuItem(Plain)
• JMenuItem mustardItem new JMenuItem(Mustard)
• JMenuItem everythingItem new JMenuItem(Everythi
  ng)

6
Menus

• Now add the item to the Menu object
• hamburgerMenu.add(plainItem)
• Next add the Menu objects to the Menu Bar
• menuBar.add(hamburgerMenu)

7
Menus

• Selecting a menu item will generate an action
  event.
• You need to install an action event listener for
  each menu item
• plainItem.addActionListener(this)
• Adding menu items listeners is easy but TEDIOUS.

8
Cut and Paste example

• JMenu menu new JMenu(Edit)
• item new JMenuItem(Cut)
• item.addActionListener(this)
• menu.add(item)
• item new JMenuItem(Paste)
• item.addActionListener(this)
• menu.add(item)
• menuBar.add(menu)

9
Reacting to menu events

• Public void actionPerformed(ActionEvent evt)
• if (evt.getSource() instanceof JMenuItem)
• String arg evt.getActionCommand()
• if (arg.equals(Cut)) do something
• else if (arg.equals(Paste)) do something
  else

10
Menu Items

• Adding
• adds a menu item
• Removing
• removes a specific item from the menu
• Inserting
• adds a new menu item (or submenu) to the menu at
  a specific index
• Gray-out menu items

11
Menus

• Icons on a menu item
• Icon hamburgerIcon new (smallHamburger.gif)
• item new JMenuItem(Plain, hamburgerIcon))
• hamburger.add(item)

12
Checkboxs on menu items

• Checkbox - when the user selects the menu item,
  the item automatically toggles between checked
  and unchecked.
• JCheckBoxMenuItem readonlyItem
• new JCheckBoxMenuItem(Read only)

13
Radio buttons on menu items

• Radio button menu items work just like regular
  radio buttons. You must add them to a button
  group. When one of the buttons in the selected,
  all others are deselected.

14
Radio buttons on menu items

• ButtonGroup group new ButtonGroup()
• JRadioButtonMenuITem plainItem
• new JRadioButtonMenuItem(Plain)
• plainItem.setSelected(true)
• JRadioButtonMenuItem everythingItem
• new JRadioButtonMenuItem (Everything)
• group.add(plainItem)
• group.add(everythtingItem)

15
Popup menus

• A pop-up menu is a menu that is not attached to a
  menu bar but that floats somewhere on the frame
  or panel.
• JPopupMenu popup new JPopupMenu()
• You then add menu items in the usual way.
• You must specify the parent component and the
  location of the popup
• popup.show(panel, x, y)

16
Popups

• Pop-up trigger
• install a mouse listener
• add code for the mouse handler
• public void mouseReleased(MouseEvent e)
• if (e. isPopupTrigger())
• popup.show(e.getComponent(), e.getX(), getY() )

17
Keyboard Mnemonics

• It is a real convenience for the experienced user
  to select menu items by keyboard mnemonics.
• JMenuItem cutItem new JMenuItem(Cut, T)
• To select a top-level menu from the menu bar, you
  hit ALT the mnemonic letter
• JMenu helpMenu new Jmenu (Help)
• helpMenu.setMnemonic(H)

18
Accelerators

• Accelerators are keyboard shortcuts that let you
  select menu items without ever opening a menu.
• E.g., CTRLO and CTRLS in many programs allow
  the user to Open and Save items in the File menu.

19
Accelerators

• setAccelerator method will attach an accelerator
  key to a menu item
• E.g., the following will attach the accelerator
  CTRLO to the openITem menu item
• openItem.setAccelerator(KeyStroke.getKeyStroke(Key
  Event.VK_O, InputEvent.CTRLMASK))
• When the user presses the accelerator key
  combination, this will select the menu option and
  fires an action event, as if the user had
  selected the menu option manually