CSSE221: Software Dev. Honors Day 9

CSSE221: Software Dev. Honors Day 9 • Announcements • HW3 passed back, follow link from HW3 to its solution. • Questions on GUIs? • No baby yet…

Capsule Deliverables • Please email the quiz, key, and summary to me by 7:30 am on the day you are presenting. • Send .doc files • (If you get them to me by 3pm on a weekday before you present, I’ll still print them) • Lessons from week 1: • Nice research and summarization! • Proofread your stuff. Everyone else will see it. • 1-page quizzes are good (or staple) • Summaries don’t have to be verbose, just dense with info.

This week: Fifteen assignment • Monday: • GUIs using Java’s Swing library • Tuesday: • Fifteen specification • EventListeners: responding to user input • Intro to UML as a design tool • Time to work on project • Thursday: • Anonymous classes (capsule) • Function objects and comparators (capsule)

“Fifteen” Questions on Specification?

Fifteen Teams Repos is csse221-200810-<usr1>-<usr2>. If solo, use your personal repos. • beltonj1-fishmad • bennetrn-leveyjr • bennindp-speyerea • crockeea-morrisps • devorejd-priestjs • lundgrpb-skilessa • johnsoad-smithny • sullivja-wentztj • mcginnda Discuss how to pair-program

Event-driven Programming: What? • We want our program to respond to events • Mouse motion, mouse clicks, button presses, menu selections, … • The Java window manager generates a huge number of events • Whenever any of these happen • We need to listen for specific events class Foo implements MouseListener { … }

Event-driven Programming: How? • Implement the BlahListener interface class Foo implements MouseMotionListener { … // We promise to implement these. void mouseDragged(MouseEvent e) { System.out.println(“Hey, stop pulling me!”); } void mouseMoved(MouseEvent e) { System.out.println(“The mouse is moving!”); System.out.println(e.getX() + “ “ + e.getY()); } }

Event-driven Programming: Which? Interface, that is… • MouseMotionListener • For receiving mouse motion events (movement and dragging) on a component. • MouseListener • For clicks and other mouse events (click and double-click, mouse enters component) • ActionListener • For component-defined actions (such as pressing a button) • KeyboardListener • ChangeListener • For components in which we only care about change (like sliders) See the API spec. for which methods you need to write

Listeners • Need 3 things! • Responder implements ActionListener interface • This means it implements actionPerformed method: public void actionPerformed(ActionEvent e) { // what happens when button is pressed } • The responder must add the listener: Say a frame has a button. this.button.addActionListener(this); Listens Responds (this is the frame, but could be a panel or even the button itself)

E.g. Button in a Panel • Button is the event source • Panel has to respond to the event and therefore must listen for events. public TopPanel extends JPanel implements ActionListener { private JButton changeColor; … public TopPanel(){ this.changeColor = new JButton(“Click to change color”); this.changeColor.addActionListener(this); //Add the listener to the source this.add(changeColor); } public void actionPerformed(ActionEvent e){ //Change the background color of the panel } }

Do I have to write a whole separate class in its own file, just for an actionPerformed method? • No! You could use an anonymous class or a function object • More on those next class • Funny that that’s the ordering of topics…

Finish demo together • Draw the UML for all classes so far • Add the listeners. • What other connections do I need? • Look at its Iterative Enhancement Plan together • Code • Sliders are similar, I used the Java Swing Tutorial for some ideas.

Start Fifteen Spec now • You need to do 2 things before you start coding: • Show us your UML • Show us your Iterative Enhancement Plan

UML ideas • List of components • For each component • Extends a class? • Implements interfaces? • Creates instances of other components? • Has instances of other components? • For which objects can I use the default Java version and which do I need to extend? • Frames, panels: extend • Text boxes: use Java’s • Buttons: it depends • Do now with another team (so groups of 4) on a whiteboard.

Iterative enhancement plan • Iterative enhancement plan: • A series of stages (and substages) • by which to develop the application, • with each stage testable by running the application • Such a plan ensures that you always have code that works • Each stage must be testable by running the application • No looking at code! • So “implement the Dud class” is NOT part of an iterative enhancement plan • It is OK for some stages to include throw-away code • The stages should be about the same size/difficulty

CSSE221: Software Dev. Honors Day 9