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Example Program

Example Program. DemoLowLevelEvents.java. DemoHighLevelEvents.java. Example Program. DemoActionEvents.java. DemoFocusEvents.java. Basic Widgets. GUI goo. Outline. What is a widget? Buttons Combo boxes Text components Message boxes. What is a Widget?.

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Example Program

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  1. Example Program DemoLowLevelEvents.java DemoHighLevelEvents.java

  2. Example Program DemoActionEvents.java DemoFocusEvents.java

  3. Basic Widgets GUI goo

  4. Outline • What is a widget? • Buttons • Combo boxes • Text components • Message boxes

  5. What is a Widget? • Widgets are interactive objects - the basic building blocks of graphical user interfaces • Generally meant to metaphorically suggest real-world controls. • Examples: buttons, menus, scrollbars. • More complex examples: windows or dialog boxes which also contains other widgets • Widgets have some behaviour: they respond to input and they change what they're displaying. • Used for both input and output • Input - information and commands • Output - information and application status

  6. Widgets • User interface toolkits (such as Swing) provide programmers with easy ways to display and use widgets and sometimes to design their own widgets. • An important part of user interface design is choosing and laying out widgets on the screen • Widgets are the most obvious visual contribution of GUIs. They're ideally intuitive. They're fun. They're familiar. They occur again and again so users become accustomed to using them.

  7. Outline • What is a widget? • Buttons • Text components • Combo boxes • Message boxes

  8. What is a Button? • An individual and isolated region of a display that can be selected by the user to invoke a state or command • Designed to look like physical buttons to suggest they can be “pushed” (like physical buttons) • Four types • Push buttons - invoke a command • Radio buttons - enable a state and indirectly disable one or more other states • Checkboxes - toggle a state on/off • Modal buttons – hybrid of push button and checkbox (aka toggle buttons)

  9. Push Buttons • The most common type of button • Pushed (“clicked”) to invoke a command • Three ways to organize push buttons… • Isolated • An individual button in a window • Pushed (“clicked”) to invoke a command (e.g., Cancel, OK, Close, Preview) • Menus • A menu is simply a popup collection of buttons • Toolbars • A collection of buttons with commonly used functions • Presentation is “persistent” (rather than popup, as with menus) • Usually employ a small icon, rather than text

  10. Push Button Examples Menu Toolbar Isolated Push button Push button Push button

  11. Radio Buttons • Allow a user to select one feature from a set of mutually exclusive features • Name derived from radio station selector buttons

  12. Radio Button Example Three mutually-exclusive options

  13. Checkboxes • “Checked” to turn a state on/off • When to use checkboxes • When a feature or characteristic has precisely two states and these are appropriately described as being “enabled” or “on” vs. “disabled” or “off” (e.g., lightbulb = on | off) • When not to use checkboxes • When a feature or characteristic has more than two states (e.g., season = spring | summer | autumn | winter) • When enabled/on and disabled/off are inappropriate descriptions of the states (e.g., gender = male | female)

  14. Checkbox Example Checked = Enable “show windows in taskbar” Unchecked = Disable “show windows in taskbar”

  15. Modal Buttons • A hybrid of push buttons and checkboxes • A modal button… • Looks like a push button • Toggles a state • Text or icon in button indicates the next state • E.g., “show details” vs. “hide details”

  16. Java’s Button Classes AbstractButton JButton JCheckBoxMenuItem JRadioButtonMenuItem JToggleButton JCheckBox JRadioButton

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