Transcript Graphical Interfaces

GUIs for Applets
Introduction
Applets and Swing/JFC
Alternatives to Swing
Look-and-Feel issues
Example applet graphical user interfaces
How do I build a GUI?
Conclusion
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GUIs for Applets
Applets and Swing/JFC
Swing is a kit of GUI “widgets” - it provides a simple
way to create, position and interact with standard
interface components
It is a major part of the Java Foundation Classes (c.f.
MFC, Microsoft Foundation Classes)
It is a “lightweight” component library, uses the MVC
(model-view-controller) architecture design pattern
Applets may use most Swing components
For security reasons some are restricted (which ones?)
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GUIs for Applets
Alternatives to Swing
The original GUI system for Java was called the
“Abstract Windowing Toolkit” or AWT
NB Swing is based on many of the AWT
components, either through compatible methods or
through inheritance
AWT is a “heavyweight” component library, uses the
widgets built into the underlying OS architecture
It has some OS-specific behaviour and thus some
portability problems
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GUIs for Applets
Alternatives to Swing
SWT is the Standard Widget Toolkit originally
developed by IBM as part of the Eclipse project (see
http://www.developer.com/java/other/article.php/2179061)
It is seen a “thin wrapper” over the native GUI of the
host OS – it is a “heavyweight” library
It is not OS-specific but was originally designed to
run in MS Windows
SWT attempts to use the strengths of the Swing and
AWT approaches while staying simple and quick
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GUIs for Applets
Examples
Simple visual
applet with mousesensitive imagebased components
Note that the title
bar is not settable
This is a Swingbased Japplet
running in Win XP
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GUIs for Applets
Swing Example
Quite a lot of components
in this simple applet
JLabel, JCheckBox,
JTextArea, JComboBox,
JButton, JRadioButton
This applet will look very
similar in any graphical OS
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GUIs for Applets
Swing Example
This example
shows most of
the simple Swing
components
The GUI is XWindows
http://commons.wikimedia.org/
wiki/Image:Gui-widgets.png
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GUIs for Applets
SWT platform-specific examples
The Standard Widget Toolkit (SWT) library uses
heavyweight components
Tied to the look-and-feel of the host OS
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GUIs for Applets
SWT – a familiar example
Eclipse has
one of the
best-known
examples of
SWT in action
Looks good
and works
well
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GUIs for Applets
Building a GUI
Choose AWT, Swing (recommended) or SWT
Learn about component types, event handlers and
layout options – documentation and examples
Design a user interface and critically evaluate it
Revise and repeat!
For background on development in AWT, with
reference to Swing, see “Graphical User Interface
(GUI) Fundamentals” (old article)
[http://www.wirelessdevnet.com/channels/java/training/javagui.html]
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GUIs for Applets
Conclusion
There are varied ways to build GUI applications in
Java Applets
Different approaches have different strengths and
weaknesses
Swing is often a good choice (widely supported,
flexible, elegant but quite complex)
Predefined widgets/components are available for
most tasks
Designing a good interface is hard
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GUIs for Applets
Optional Further Reading
Swing article on Wikipedia
[http://en.wikipedia.org/wiki/Java_Swing]
Applet article on Wikipedia
[http://en.wikipedia.org/wiki/Java_applet]
Standard Widget Toolkit article on Wikipedia
[http://en.wikipedia.org/wiki/Standard_Widget_Toolkit]
Swing documentation (Sun)
[http://java.sun.com/javase/6/docs/api/index.html]
How to make Applets (Sun)
[http://java.sun.com/docs/books/tutorial/uiswing/components/applet.html]
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