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Java Intro
Chris North
cs3724: HCI
Presentations
• john randal, • tom shultz
• Vote: UI Hall of Fame/Shame?
Quiz
• Visualization design principles:• show me the data
• Increase info density
• Overview first, zoom&filter, details on demand
• …
• How to map data to graphics?• 1. Data items become marks
• 2. Data values map to mark attributes
More Quiz
• Multi-dimensional data?• multiple attributes
• Types of scale in multi-dim data?• # points
• # attributes
• ranges of data values
• 3 multi-dim visualizations?• par coords
• Spotfire: mapping, brush&link, DQ
• Tablelens: graphical table
Data Scale
• # of attributes (dimensionality)
• # of items
• # of possible values (e.g. bits/value)
Spotfire
• Multiple views: brushing and linking
• Dynamic Queries
• Details window
TableLens (Eureka by Inxight)
• Visual encoding of cell values, sorting
• Details expand within context
Parallel Coordinates (XmdvTool)
• Par coords: 10-100 attrs, <1000 points
• Tablelens: 10-100 attrs, 1000, more by grouping
• Spotfire: 10 attrs, more w/ DQ, 100,000 pts
Homework #2: Info. Vis. Tools
• Get some data:• Tabular, >=5 attributes (columns), >=500 items (rows)
• Use 2 visualization tools + Excel:• Spotfire, TableLens, Parallel Coordinates
• Mcbryde 104c
• 2 page report:• Discoveries in data
• Comparison of tools
• Due:• Feb 19: A-K
• Feb 21: L-Z
Technologies
• VisualBasic• Fast prototyping• Help stinks• Lack of control, multi-threading, POWER!• Code tends to be ugly, variation, arbitrary
• Java• Power• Lots to learn• Slow development, except jbuilder?• Complexity• Tons of code• Help is good
Java materials
• Java 2 = sdk 1.2 or better• http://java.sun.com/j2se/
• Documentation:• http://java.sun.com/docs/
• Tutorials, reference, API
• Sams “Teach yourself Java2 in 21 days”
• Borland JBuilder 6• http://www.borland.com/jbuilder/personal/
• Free! Cross between VB and VC++
Java differences• Basic statements identical to C++• Object-oriented only!• No .h files• Garbage collection: no delete• No pointers (object references only)• GUI: AWT, Swing• Applet/application• Single inheritance, interfaces• Packaging• No global vars• Error Handling, exceptions (try, catch)
• E.g. Array bounds checking
• Security• Objects, components
Java compiling
• Code: • myclass.java (text file)
• Compile: •javac myclass.java• Creates: myclass.class (byte code)
• Run: •java myclass• Java virtual machine, interpets/compiles (machine code)
• Packaging: jar
• Or use JBuilder, like VC++
Java Applications
• Run from command line, like .exe
• HelloWorldApp.java:Class helloWorld {
public static void main(String[] args){
system.out.println(“Hello World!”);
}
}
• javac HelloWorldApp.java• Java HelloWorldAppHello World!
• Can be main( ) in any/all classes
Java Applets• Run in a web browser, like .ocx control• HelloWorldApplet.java:Import java.awt.*
public Class helloWorld extends javax.swing.JApplet {
public void init(){
setBackground(Color.white);
}
public void paint(Graphics g){
g.setColor(Color.black);
g.drawString(“Hello World!”, 10,10);
}
}
• javac HelloWorldApplet.java• appletviewer HelloWorldApplet
Hello World!
Java Applets
• HelloWorldApplet.html:<html><body>
<applet code=“HelloWorldApplet.class” height=100 width=200>
Need java.
</applet>
</body></html>
• Put .html and .class on website• Java plug-in
Hello World!
Applet Methods
• init( ) - initialization
• start( ) - resume processing (e.g. animations)
• stop( ) - pause
• destroy( ) - cleanup
• paint( ) - redraw stuff (‘expose’ event)
Applet Security
• No read/write on client machine
• Can’t execute programs on client machine
• Communicate only with server
• “Java applet window” Warning
• Certificates
JBuilder
Upcoming Java Topics
• GUIs: Swing, AWT, MVC
• Event handling, listeners
• Graphics
• Animation, threads
• Components, JavaBeans
• Databases, JDBC
Next
• Midterm: feb 26, tues
Presentations: proj1 design or UI critique
• Next Tues: mohamed hassoun, aaron dalton
• Next Thurs: nadine edwards, steve terhar
Project 2: Java
• Teams due today
• Get started on design
• 0: form teams of 3 (feb 14)
• 1: design (feb 28)
• 2: initial implementation (mid march)
• 3: final implementation (early April)
