Advanced GUI Components

1
Chapter 2

• Advanced GUI Components

2
Topics

• how to render HTML and Rich Text Format (RTF)
  pages
• how to do split panes and tabbed panes
• how to create MDI (multiple-document interfaces)
• how to do drag and drop
• how to use the Command Design Pattern (Action
  Interface)
• what Java mechanisms exist for multiple languages
  and countries
• what Java mechanisms exist for disabled users
  (not covered)

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HTML and the JEditor Class

• JTextComponent - base class for other text
  components
• JTextField - single-line text component used for
  simple user input, displaying calculation
  results, etc.
• JPassword, subclass of JTextField, used for
  obtaining passwords.
• JTextArea provides larger visible area, used for
  plain-text documents.
• JEditorPane provides enhanced text-rendering
  capabilities.  Can render html and rtf (rich text
  format) documents.  Enables hyperlinks if text is
  not editable make your own web browser!
• JTextPane renders only styled documents, not
  plain text.  Use for fine control over visual
  display of document.

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Enhanced Pane Options

• JSplitPane provides a divider which users can
  reposition. 
• JTabbedPane uses folder-style tabs to provide
  access to different panels.
• JScrollPane provides a container that enables
  scrolling

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Multiple-Document Interfaces

• Multiple Document Interfaces (MDI) allow users to
  view multiple documents in a single application.
• Each document appears in a separate window.
• JDesktopPane and JInternalFrame are used to build
  MDI applications.
• JDesktopPane is the application's "desktop."
• JInternalFrame is similar to JFrame, with a title
  bar and buttons to iconify etc. 

6
Swing toolbars

• JToolbar allows toolbars to be added to GUI
• Can modify appearance, "dock" toolbar on top,
  side or bottom, can be a floating toolbar. 
• A toolbar is a container, so it can contain other
  GUI components. 
• Orientation specifies how child components are
  arranged.  Default is horizontal. 

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Command design pattern/Action Interface

• Design issue it's good for an application to
  provide multiple ways to perform a function
  (e.g., menu, toolbar, pop-up menu).  BUT, don't
  want to repeat functionality in multiple places.
• Solution define functionality once in a reusable
  object that can be accessed via menu, toolbar,
  etc. 
• Action interface defines required methods for
  Command design pattern.
• Extends ActionListener so it can process
  ActionEvents generated by GUI components.
• Uses an actionPerformed method that is invoked
  when the user requests an action (e.g., by
  clicking a button). 
• Can add an Action to a JMenu, which causes the
  JMenu to create a JMenuItem, using the Action
  properties to configure the JMenuItem. 
• Ex fileMenu.add(exitAction)
• // creates menu item with properties determined
  by exitAction
• Can enable/disable all GUI components by
  enabling/disabling the Action.  Action items are
  enabled by default.  Can use setEnabled to change.

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Command/Action cont.

• Class AbstractAction implements Action. It's
  abstract because actionPerformed is not defined. 
  It also implements Cloneable and Serializable.
• Each Action has properties (key/value
  combination).  The keys are
• NAME (component label)
• SHORT_DESCRIPTION (tool tips)
• SMALL_ICON
• MNEMONIC_KEY (menu items)
• ACCELERATOR_KEY (Ctrl)
• ACTION_COMMAND_KEY (retrieves command string used
  in ActionEvents),
• LONG_DESCRIPTION (e.g., for help).
• Use putValue to set properties.

9
Drag and Drop

• Two Java APIs used in drag-and-drop data
  transfers
• java.awt.datatransfer enables copying and moving
  within a single application.
• Data can be transferred from a data source to a
  data target.
• API enables programs to recognize drag-and-drop
  gestures.
• Class DropTarget is associated with a Component
  via a call to the DropTarget constructor.   Other
  optional parameters to the constructor include an
  integer that represents acceptable actions, a
  DropTargetListener and a boolean that determines
  whether the target is currently accepting drops.
  
• Methods of DropTarget include some which deal
  with events (e.g., drop, dragOver), methods
  dealing with auto scrolling (e.g.,
  updateAutoScroll), methods to manage listeners
  (e.g., removeDropTargetListener) and others.

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Drag and Drop cont.

• DropTargetListener interface includes methods
  dragEnter, dragExit, dragOver, drop and
  dropActionChanged.
• DnDConstants include ACTION_COPY, ACTION_MOVE,
  ACTION_LINK and ACTION_NONE. 
• Class DropTargetDropEvent is delivered when an
  object is dropped.  It reports the source drop
  actions (DnDConstant, drop options supported by
  source) and the user drop action (depends on
  modifier keys ctrlshift link, ctrl copy,
  shift move).  User drop action will be
  ACTION_NONE if the selected option is not
  supported by the drag source.
• The getTransferable method of DropTargetDropEvent
  can be used to access the Transferable object
  associated with the drop.
• Class DataFlavor represents the data format used
  during drag and drop, in the clipboard, or in a
  file system.  It provides static constants that
  can be used for comparison to common formats.

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Drag and Drop
Source
Target
JEditorPane (our program - WebBrowserPane)
html doc rtf doc text doc
setDropTarget
associates handler
DropTargetHandler (implements DropTargetListener)
dragEnter dragExit dragOver drop dropActionChanged
drop get Transferable from event check
DataFlavor (image, fileList, string, MIME
etc.) event.acceptDrop process (we
goToURL) event.dropComplete indicates success
12
Internationalization

• Process of preparing an application for
  distribution in multiple locales
• A locale identifies the language, currency,
  character set, date formats etc. for a particular
  country or region.
• To internationalize, replace hard-coded strings
  such as labels, tooltips etc. with strings
  contained in a ResourceBundle.
• The ResourceBundle class includes a static method
  getBundle which is used to load application
  specific strings.
• The getString method of ResourceBundle is used to
  retrieve strings.  The parameter to getString
  should match one of the strings listed in the
  resource file.
• NumberFormat and DateFormat classes can use
  information about the locale when producing
  output.  For example, the format command of
  DateFormat can take both a Date and Locale as
  arguments.
• Internationalized applications must use Unicode,
  the 16-bit character code that includes symbols
  from many different languages (more than can be
  represented in the 8-bit ASCII code).  Java
  always uses Unicode, but data generated by other
  applications might not be. 

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Format of the resource file

• Files must be named properly to be associated
  with various locales.
• The filename for the default Locale is ltfile name
  matching parameter to getBundlegt.properties
• Ex StringsAndLabels.properties
• For other locales, the name is ltfile name
  matching parameter_languageCode_countryCodegt.prope
  rties
• ExStringsAndLabels_fr_FR.properties.
• Escape characters in the resource file should be
  Unicode escape sequences, which are \u followed
  by four hexadecimal digits. 
• ISO language codes are available at
  www.ics.uci.edu/pub/ietf/http/related/iso639.txt
  
• ISO country codes are available at
• www.chemie.fu-berlin.de/diverse/doc/ISO_3166.html
  

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Example

• Properties for English English language strings
  for internationalized WebBrowser application
  titleapplicationTitle Deitel Web Browser
  title for WebToolBartoolBarTitle Web
  Navigation tooltip for forward toolbar
  buttonforwardToolTip Next Page tooltip for
  back buttonbackToolTip Previous Page

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Example cont.

• Properties for French
• French language strings for internationalized
  WebBrowser tooltip for back buttonbackToolTip
  Page pr\u00E9c\u00E9dente application
  titleapplicationTitle Logiciel de Navigation
  de Deitel title for WebToolBartoolBarTitle
  Navigation des Pages sur la Toile tooltip for
  forward toolbar buttonforwardToolTip Prochaine
  Page

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Obtaining a list of Locales

• import java.text.DateFormat
• import java.util.Locale
• public class Locales
• public static void main(String args)
• // Locale class contains the default location
• System.out.println("Default locale is "
  Locale.getDefault())
• // Date Format class maintains list of all
  locales
• Locale locales DateFormat.getAvailableLoca
  les()
• String spaces " "
• for (int i 0 i lt locales.length i)
• if (localesi.getCountry() ! "") // omit
  locales with only language
• // add spaces to keep columns aligned
• System.out.println(localesi
  spaces.substring(localesi.toString().length())
• localesi.getDisplayName())

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Seeing Number Formats

• / Formats numbers, currency, and percents, first
  in the
• default locale, then using a language and
  country passed
• as program arguments.
• /
• import java.text.NumberFormat
• import java.util.Locale
• public class Numbers
• public static void main(String args)
• NumberFormat numDefault NumberFormat.getNumb
  erInstance()
• NumberFormat curDefault NumberFormat.getCurr
  encyInstance()
• NumberFormat perDefault NumberFormat.getPerc
  entInstance()
• System.out.println("Max fraction digits "
  numDefault.getMaximumFractionDigits())
• double d 12345.67899
• System.out.println(numDefault.format(d))
• System.out.println(curDefault.format(d))
• System.out.println("Min fraction digits "
  numDefault.getMinimumFractionDigits())
• System.out.println(perDefault.format(d))

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Seeing Date Formats

• import java.text.DateFormat
• import java.util.Locale
• import java.util.Calendar
• import java.util.GregorianCalendar
• import java.util.Date
• public class DateTime
• public static void main(String args)
• Calendar calendar new GregorianCalendar(2000
  ,6,4,14,10,5)
• Date theFourth calendar.getTime()
  
• DateFormat fullDefault DateFormat.getDateTim
  eInstance
• (DateFormat.FULL,DateFormat.FULL) // style for
  date and time
• DateFormat longDefault DateFormat.getDateTim
  eInstance (DateFormat.LONG,DateFormat.LONG)
• DateFormat mediumDefault DateFormat.getDateT
  imeInstance (DateFormat.MEDIUM,DateFormat.MEDIUM)
  
• DateFormat shortDefault DateFormat.getDateTi
  meInstance (DateFormat.SHORT,DateFormat.SHORT)
• DateFormat justDate DateFormat.getDateInstan
  ce()
• DateFormat justTime DateFormat.getTimeInstan
  ce()
• System.out.println(fullDefault.format(theFourt
  h))
• System.out.println(longDefault.format(theFourt
  h))

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MessageFormat

• MessageFormat provides a means to produce
  concatenated messages in language-neutral way.
• Ex The date is Tuesday, July 4, 2000
• First part (The date is ) is constant.
• Actual date format will vary with location.
• String s The date is 0
• String formatted MessageFormat.format(s,
  arguments)

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Chapter 2 Exercises

• Read/execute web browsers. Next homework will
  involve web browsing.
• Add another action to ActionSample. Be sure to
  update toolbar, menu and add a button.
• Add another country to BrowserLauncher.