Comp 170-003 , MWF 2:45-3:35 25EP-201, Lab M 4:15-5:05 or earlier

Week	start
1	8/27
2	9/3*	Labor Day
3	9/10
4	9/17
5	9/24
6	10/1	Exam 1: Mon
7	10/8*

8	10/15
9	10/22
10	10/29
11	11/5
12	11/12	Exam 2: Mon 
13	11/19	Thanksgiving: no lab
14	11/26
15	12/3	last class


Week 1

intro
text
2 exams 
TA: Maria Saenz

Syllabus/groundrules

Who has programmed, and, if so, in what?
Need for IDs and Passwords
Structure of Labs

Programming versus problem-solving

actions versus objects
	move the car
	take the car and move it
        our book has a very strong focus on objects

"Car" as a class, versus 1995 Dodge Caravan, a specific car (an instance).
Instances have properties, and can have actions applied to them.

The Shapes class, and some instances.
====================================

	creating instances on the object bench; multiple instances
	simple METHODS: makeVisible, moveRight, moveDown
	methods with PARAMETERS: moveHorizontal
	data types and objects: int, Circle, String
	State: object inspector
	
programming:
        comments, syntax, whitespace, visual style
        identifiers
        reserved words
        case sensitive
        overall format of classes; public static void
        println
        
        FIELDS define object state
        	fields of square, circle, triangle
        

programming issues
        compilation v execution

        java v bluej
        variables, types
      
A simple class with some strings
A class: 	String
some instances:	"hello", "peter", "loyola", "foo"+"bar"
	creating strings, with +


The *class* defines some OPERATIONS too.
Classes = data + operations


the pldHello class
==================
	basics of string output: System.out.println()
	where string output goes in BlueJ
	hi()
	demo2()
	    why some things don't work as it seems they should
	    1 + "hi" versus "hi"+1


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Wednesday, August 29

READ: Chapter 1, start TicketMachine in Chapter 2

	pldHello
	picture
	student

In java, *almost* everything is an object.
But there are "primitive" types too: int, double/float.

String is a class, though.

Convention: class names are capitalized, instance names are not.

It is convenient to think of programs as a bunch of operations on objects.
Some of these operations require parameters.
Note that sometimes parameters are other objects, and sometimes
it's not clear which object should be the one acted upon and which the parameter.

	s.compareTo(s2)
	
Note also that some operations CHANGE the object ("mutators"), and some don't ("accessors")
If change occurs sometimes and not others, it's still a mutator.


String examples; pldHello class

    escape chars \", \n, \t, \', \\
    String w, x, y, z;
    w = "peter"
    w = new String("peter");	// rare
    x = w;
    y = new String(w);
    w.replace('p', 'P');
    w.toLowerCase();

Note last two are NOT mutators!
	what is a mutator??

Shapes class, subclasses, multiple instances of Circle

Circles, etc have INTERNAL STATE. Look at on the object bench, 
and then in the class code.

What about Shape itself?

Making a picture

Picture demo
============
	In Lab 0 you created objects on the Object Bench, 
	and positioned them "manually", by moving them.
	
	Picture: object creation within a program
	"automated" repositioning
	
	What happens if we create a picture, invoke setblackandwhite,
	and *then* draw?

	Try commenting something out and recompiling 
	(esp in setblackandwhite).

	Second sun, red
		why doesn't setblackandwhite work?

Enrollment example
==================
	creating objects (students) to add
	using the inspector
	object names; objects as parameters

labclasses project:

1. create a student. What are the parameters? Just two strings? 
Could they be firstname and lastname? Oops... no.

Why do you think student_number is a string and not an int?

2. Add some credits.

3. Call some methods that return values.

End of class

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Friday, August 31

Labclass
TicketMachine

Labclass object

Notice that in the Shapes and Picture examples, methods did NOT return values!
They just drew things. But many of the Student methods have return values.

4. Now let's create a LabClass object, and put some students into it.
This illustrates the use of passing objects as parameters, using the name!
(Actually, we just click)
You must already have created the objects on the Object Bench.

What about duplicates?

LabClass project: Where is LabClass *putting* all these students?
Look for the ArrayList structure.
Identify where a new student is put, how we add a student, how we find out how 
many have been added, and how we print them all out. This last requires a loop.

What about populate()? What if populate() runs into the limit?


====================================

(Normally in java you don't have the Object Bench to use to tweak individual objects;
you have to write a program to do that.)

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===========================================================================================


Note that the Shapes and Picture programs cannot run "stand-alone"; 
as examples they rely on use of the Object Bench in BlueJ.
Making them standalone isn't too hard; a standalone program
begins with a procedure called main(). But there are a few 
details to sort out.



	

================

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3. Now go on to the TicketMachine.
Simple one:
	variables: private data
	public/private
	ctor
	getPrice
	getBalance
	insertMoney
	printTicket
	
	Ticketmachine "invariant": balance & total are always updated properly.
	
	Exercises 2.7/2.8: change to "class public Ticketmachine", leave out public entirely
	
	Fields/Ctors/Methods
	
	Note that the ctor does NOT return a value!
	You can write functions that don't return a value by putting "void" there.
	
	Look at fields through the Inspector
	
	Formal v Actual params in ctor
	
	Which variable is which? Figuring out what the fields are
	
	accessors & mutators
	
	
	Make TicketMachine print a serial # on each ticket
		private int serialNum
	Add a method ticketCount()
	
	
	What if we don't put in enough money?
	What if we put in too much?
	What if we insert -100000 cents?
	What if the initial ticket price is negative?
	
	This brings us to if-statements: p 36
		
4.	CORRECTION to ticketmachine: 
	improved logic to printTicket(): make sure enough money was inserted
	
	class vars v local vars
	_ convention?
	
	Overview of ch 2: 
		fields, ctors, methods (accessor/mutator), parameters, assignment, return, if
	
	review structure of a class:
		fields 		almost always private
		ctors		usually public; no return type
		methods		usually public; must have return type (or "void")
			accessors generally return a value
			mutators may or may not.
			
	At least as far as fields go, an object looks like a DATABASE RECORD.
	ISOM 370 registrants take note:
	
	methods calling other methods

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