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Developing User Interfaces

(DUI)

Chris North

cs3724: HCI

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GUI Development: Goals

1. Learn generalGUI programming concepts GUI components

Layout

Event-based programming

Graphics

Animation

2. Learn Java Swing

Layout managers

Listerners

2D graphics Threads

Then: can learn other languages quickly VB, C#, Xwin, Java 49

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Intro to Java

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Why Java?

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Java materials

Java 2 = sdk 1.2 or better

http://java.sun.com/j2se/

Documentation:

http://java.sun.com/docs/

Tutorials, reference, API

Borland JBuilder 6 http://www.borland.com/jbuilder/personal/

Free! Cross between VB and VC++

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Java differences Basic statements identical to C++

Object-oriented only! No .h files

main() is inside a class

No global variables

No pointers (object references only)

No delete: automatic garbage collection

Single inheritance only, interfaces

Applet/application

GUI: AWT, Swing

Packaging Error Handling, exceptions (try, catch)

E.g. Array bounds checking

Security

Components: beans

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Java compiling

Code:

hello.java (text file)

Compile:javac hello.java

Creates: hello.class (byte code)

Run:

java hello Java virtual machine, interpets/compiles (machine code)

Packaging: jar

Or use JBuilder, like VC++

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Java Applications

Run from command line

hello.java:class hello {

public static void main(String[] args){System.out.println(Hello World!);

}

}

javac hello.java

java hello

Hello World!

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Typically create objects

hello.java:class hello {

public static void main(String[] args){

// Create and use objects

hello h = new hello();

}

public hello(){ // Constructor

}

}

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Many Classes

Compile each separately Can be main( ) in any/all classes

hello.java:class hello {

goodbye g;

public static voidmain(String[] args){

}

goodbye.java:class goodbye {

public static voidmain(String[] args){

}

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Hmmm

dir

hello.class

goodbye.class

blah.classfoo.class

bar.class

areyouawakein.class

Java ???

RunMe.bat:java hello

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JBuilder

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Java Applets

Run in a web browser hello.java:import javax.swing.*;

class hello extends JApplet {

public voidinit(){

getContentPane().add(

new JLabel(Hello World!) );

}

}

javac hello.java

appletviewer hello HelloWorld!

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Java Applets in HTML

hello.html:

Need java.

Put hello.html andhello.class on website

Java plug-inHelloWorld!

hello.html

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AppletMethods

init( ) - initialization

start( ) - resume processing (e.g. animations)

stop( ) - pause

destroy( ) - cleanup

paint( ) - redraw stuff (expose event)

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Applet Security

No read/write on client machine

Cant execute programs on client machine

Communicate only with server

Java applet windowWarning

Certificates

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Upcoming Java Topics

GUIs: Swing, AWT,MVC

Event handling, listeners

Graphics

Animation, threads

Components, JavaBeans

Databases, JDBC