More AWT

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More AWT
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Menus in Java

• Following three classes are used to create menus
  in java.
• MenuBar
• Menu
• MenuItem

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Java.awt.MenuBar
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Java.awt.MenuBar

• MenuBar is always added on top of the screen
• java.awt.MenuBar is instantiated as follows
• MenuBar mb new MenuBar()
• Associate this menubar with a window
• Frame f new Frame()
• f. setMenuBar(mb)

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Java.awt.Menu

• Menu represents the drop-down menu attached to a
  menu bar
• Instantiate a menu Item
• Menu file new Menu("File")
• Associate this Menu with the MenuBar
• mb.add(file)

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Java.awt.Menu
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Java.awt.MenuItem

• Every Item on a Menu is represented by an object
  of MenuItem class
• Create Menu Item
• MenuItem add new MenuItem("Add Item")
• MenuItem exit new MenuItem(Exit)
• Associating these items with Menu
• file.add(add)
• file.add(exit)

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Java.awt.MenuItem
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Making Menu Item work

• You can add an actionListener to this menu Item
  to make it work.
• Code written in ActionPerformed is executed
  whenever this menu item is clicked

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java.awt.Panel

• Panels are dependent containers
• You can add other components to Panels
• You can set Layout of Panels
• Panels can eventually be added to other
  Containers (including Panels)

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Panels

• Creating Panels
• Panel p new Panel()
• Setting Layout
• p.setLayout(new FlowLayout())
• Adding Components to a Panel
• p.add( new Button(OK))
• Adding panel to the frame
• Frame f new Frame()
• f.setLayout(new BorderLayout())
• f.add(p, BorderLayout.CENTER)

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• This screen has 2 panels.
• One on the East, and the other on the south

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Checkbox

• java.awt.Checkbox represents an on-screen checkbox

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Checkbox

• Creating Checkboxes
• Checkbox c1, c2, c3
• c1 new Checkbox("hey!")
• c2 new Checkbox("whoa!")
• c3 new Checkbox("wow!")

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Adding Checkboxes to Panel

• Panel east new Panel()
• east.setLayout(new FlowLayout())
• east.add(c1)
• east.add(c2)
• east.add(c3)

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Adding the Panel to Frame

• Frame f new Frame()
• f.setLayout(new BorderLayout())
• f.add(east, BorderLayout.EAST)

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Resulting Screen
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Checkbox Groups

• A number of Checkboxes can be grouped into
  Checkbox Groups
• Only one checkbox can be in a CHECKED state when
  associated with a checkbox group

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Checkbox Group

• Only one element Checked
• Also known as Radio Button

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Creating Checkbox Group

• CheckboxGroup cbg new CheckboxGroup()

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Associating Checkboxes with CheckboxGroup

• Checkbox c4, c5, c6
• c4 new Checkbox("yes", cbg, true)
• c5 new Checkbox("no", cbg, true)
• c6 new Checkbox("may be", cbg, true)

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Adding to Panel

• Panel south new Panel()
• south.setLayout(new FlowLayout())
• south.add(c4 )
• south.add(c5)
• south.add(c6)
• Frame f new Frame()
• f.add(south, BorderLayout.SOUTH)

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Resulting Screen
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List

• Class java.awt.List Represents the List-Boxes
• Creating a ListList myList new List()
• Then simply add this list to the Frame
• f.add(myList, BorderLayout.CENTER)

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Adding Elements to the List

• l.add(Message 1")
• l.add(Message 2")
• l.add(Message 3")
• l.add(Message 4")

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Resulting Screen
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Try-out Making This Screen
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Try-out Making This Screen

• Requirements
• Add a List at CENTER
• Add a Label at WEST
• Add a Panel with 3 checkboxes at EAST
• Add a Panel with 3 checkboxes (in one group) at
  SOUTH
• Add MenuBar with one FILE menu having two Items
  i.e Add Item and EXIT
• Clicking Add Item should add a string to list
• Clicking Exit should EXIT the program