Menus Pull-downs and popups

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”);

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

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

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(“Everything”):

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

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.

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);

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} –}

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

Menus Icons on a menu item –Icon hamburgerIcon = new (“smallHamburger.gif”); –item = new JMenuItem(“Plain”, hamburgerIcon)); –hamburger.add(item);

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”);

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.

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);

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);

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() ); –}

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’);

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

Accelerators setAccelerator method will attach an accelerator key to a menu item E.g., the following will attach the accelerator CTRL+O to the openITem menu item: openItem.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK _O, InputEvent.CTRL+MASK)); 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