java swings for beginners

1. Java Swing - Lecture 1
An Introduction
Milena Radenkovic
(mvr@cs.nott.ac.uk)
slides originally by Chris Coleman

2. 2
Timeline
• 26th
Oct (Now) - Java Necessaries, Swing Basics
• 27th
Oct - Components and Containers
• 3rd
Oct - Layout Management
• 9th
Nov - Event Handling and Listeners
• 10th
Nov - Graphics with Swing
• Java Labs TBA

3. 3
Before we Start… (1)
• Swing is all Java.
• You must know about, and understand:
 Classes / Objects
 Method Overloading
 Inheritance
 Polymorphism
 Interfaces
 How to read the Java2 API Documents

4. 4
Before We Start… (2)
• If Java is a problem – learn NOW, not later
when the coursework is due!
 Labs
 Come to the labs and help is there for both Java and
Swing.
 Web
 Use the Sun/Java tutorials
 Plenty of web resources out there, even the PRG notes
 Read a book?

5. 5
2D interface programming
toolkits
• Tcl/Tk
• Motif/UIL
• IDEs (e.g. VB, MSVC++/MFC)
• Java AWT – the beginnings
• Java JFC Swing (Java2 - JDK >= 1.2)
• JBuilder and other Java IDEs
• etc…

6. 6
What is Swing?
• A part of The Java Foundation Classes
 Swing
 Look and feel
 Accessibility
 Java 2D (Java 2 onwards)
 Drag and Drop
 etc
• Can be used to build Standalone Apps as well
as Servlets and Applets

7. 7
On-line reading and reference
• The Java Swing trail:
http://java.sun.com/docs/books/tutorial/uiswing/
• Swing articles:
http://java.sun.com/javase/technologies/desktop/articles.jsp
• Developer Technical Articles & Tips:
http://java.sun.com/developer/technicalArticles/GUI/

8. 8
Books
• Java Swing (1998), Robert Eckstein,
Mark Loy, Dave Wood, O'Reilly
• JFC Swing Tutorial, The: A Guide
to Constructing GUIs, 2nd Edition
(2004); K. Walrath and M. Campione,
Addison Wesley

9. 9
Getting started with Swing (1)
• Compiling & running programs
 Swing is standard in Java 2 (JDK >= 1.2)
 Use:
 ‘javac <program.java>’ && ‘java <program>’
 Or JCreator / IDE

10. 10
Getting started with Swing (2)
• Computer Science Department Stuff…
 PCs
 Java 2 (1.5.0) on hard disk at csjava
 Unix (tuck and much):
 Java 2 (1.5.0) in /usr/bin (or /usr/java)
 Differences between previous versions
 http://java.sun.com/j2se/1.4.2/docs/guide/swing/SwingChanges.html
 http://java.sun.com/j2se/1.5.0/docs/guide/swing/SwingChanges.html
 Coursework marked on Win XP & JDK
1.5.0

11. 11
Getting started with Swing (3)
• Swing, like the rest of the Java API is
subdivided into packages:
 javax.swing, javax.accessibility,
javax.swing.border …
• At the start of your code - always
 import javax.swing;
 import javax.swing.event;
• Most Swing programs also need
 import java.awt.*;
 import java.awt.event.*;

12. 12
Differences between Swing and
AWT (1)
• Never mix Swing and AWT components
• If you know AWT, put ‘J’ in front of
everything
 AWT: Button
 Swing: JButton
• Swing does all that AWT does, but better
and there’s much more of it.

13. 13
Differences between Swing and
AWT (2)
• Buttons and labels can display images
• Behaviour and appearance of components
• Component shape
• Borders
• Assistive technologies
• Look and feel of the program’s GUI
 Windows – (but only on Windows, M$ issues….)
 UNIX
 GTK
 etc

14. 14
A typical Swing program
• Consists of multiple parts
 Containers
 Components
 Events
 Graphics
 (Threads)
• Now look at each in turn

15. 15
A simple Swing program -
Containers
• Containers

16. 16
Remember this about
Containers:
• The structure of containers is your design
decision and should always be thought
through in advance
 particularly for managing components
 nesting containers
• Failure to do so usually either results in a
messy interface, messy code or both.

17. 17
A simple Swing program -
Components
• Components

18. 18
Remember this about
Components:
• There are many components that make your job
much easier.
• Often, you will be able to customise an existing
Swing component to do a job for you, instead of
having to start from scratch
 Eg can extend (inherit from) the JButton class and
‘paint’ a new button over the top

19. 19
A simple Swing program -
Events
• Events

20. 20
Remember this about events:
• ‘Events’ as seen by GUIs do not happen
all that often in an application
• Consider what is happening between events
as well as during them

21. 21
A simple Swing program -
Graphics
• Graphics
• Complex drawing and
shading API.
• Can do far more than
display images.

22. 22
Remember this about
Graphics:
• There are many aspects of Swing that
allow you to achieve graphics-like things
without actually using ‘Graphics’.
• Therefore, you don’t have to use them
most of the time, and it is often easier not
to.

23. 23
A simple Swing program -
Threads
• Most simple Swing GUI applications don’t
require use of any (extra) threads
• As Swing creates event-driven programs,
all code is executed on the event-
dispatching thread

24. 24
Remember this about Threads:
The single-thread rule
“Once a Swing component has been realized,
all code that might affect or depend on the
state of that component should be executed in
the event-dispatching thread”
(with some exceptions)

25. 25
How to Learn Swing
• Don’t even try.
• Learn general framework principles and
design styles.
• Then use the API reference, and Swing
Tutorials to discover detailed usage of
each component.

26. 26
How to read Java Docs (1)
• Java 2 (J2SE 1.5.0) API Reference:
 http://java.sun.com/j2se/1.5.0/docs/api/
• Split into 3 Sections (html frames):
 Top Left: Packages
 Bottom Left: Classes in Packages
 Main Frame: Information about selected Class

27. 27
How to read Java Docs (2)
• General idea is find class, and examine main
frame for information.
• Main frame pages split into sections:
 Package hierarchy & implemented interfaces
 Class Description, and links to more info
 Nested Class Summary – Detail in separate page
 Fields - 2 types Class (static) and instance, plus fields
inherited from parent classes / interfaces
 Constructor Summary
 Method Summary & inherited methods from parents
 Detailed info on all summary sections

28. 28
Summary
• Do you know enough Java?
• 2D interface programming toolkits
• JFC/Swing
• AWT and Swing
• Getting started with Swing
• Parts of a simple Swing program
• Tomorrow: Components and Containers
• Some source code, and design styles