Tutorial 1      Lecturer: Ray Reiter          Tutor: Andria Hunter
==========                                  990106 Wed@1pm (PA105)

CSC148, Spring 1999                            Tutorial notes,  T1
==================================================================

Topics:
------------------------------
 - Introduction
 - Using the system (briefly) 
 - Java packages
 - Java refresher
 - Java classes, and static instance members


List of TAs and rooms
------------------------------
  - This tutorial section is for students whose last name
    starts from Sin-Z and who have Ray Reiter at 1:10 pm.


Introduction
------------------------------

  - Introduce yourself.  (Write your name on the board - they'll need
    to know your name if they want to get their assignments back! :-))
       - did my MSc in Computer Science here at UofT
       - did my BSc in Computer Science at UNH on a hockey scholarship
       - 2 world championships with Team Canada!
       - TAed many courses at UofT, but never 148
       - How many of you have taken CSC108?  No Java experience?
 
  - Feel free to say a few words about what you hope tutorials
    will be like:
       - purpose is not to present new material
       - bring your questions!  Don't be shy ... chances are the
            person sitting next to you has the same question!
 
  - Other places for extra help
       - Read the PC-HOTO GUIDE - system info & starting JavaWorkshop
       - Do the online homework examples
       - TA office hours in the lab
       - Instructor office hours


Using the System 
------------------------------

  - Very briefly go over these system basics:
      - login and logout 
      - web & newsgroups
      - send and read mail
      - printing
      - disks on CDFPC
      - Java Workshop
  
Java Packages
------------------------------

- We rely heavily on Java packages this term.  The students didn't
  see much of them in 108, so it'll be pretty new to them.

- The course web page has info on exactly how to set up Java WorkShop
  to manage packages for assignment 0 (although it is not required
  for assignment 0).  The course web page also contains lecture
  notes that explain packages more.


Java Refresher
------------------------------

- Get to class a minute or two early and put this up:

    public class Example1 {
        public static void main( String[] args ) {
            // Add the integers 1 through 5 and print the result.
            int result = 0;

            // >> The for loop goes here. <<
        }
    }

- Have them write the loop, in small groups if you want.  Let them
  work on it for about 2 minutes and walk around and talk to them
  during that time, then go to the board and have them tell you what
  to write.

- Some of them won't know Java.  Tell those students to write it in
  the language of their choice, but do only Java on the board.

Java classes
------------------------------

- Here is an example that uses an array of objects...

    public class Student {
        private String myName;
        private int myID;

        public Student( String name, int id ) {
            myName = name;
            myID = id;
        }

        public void setName( String newName ) {
            myName = newName;
        }

        public String getName() {
            return myName;
        }

        public void setID( int newID ) {
            myID = newID;
        }

        public int getID() {
            return myID;
        }
    }

    public class Section {
        private Student[] students;
        private int numStudents;

        public Section( int numStudents ) {
            students = new Student[numStudents];
        }

        public void addStudent( Student s ) {
            students[numStudents++] = s;
        }

        public Student findStudent( int id ) {
            for (int i=0; i<numStudents; i++) {
                if (students[i].getID() == id) {
                    return students[i];
                }
            }
            return null;
        }
    }

    public class Main {
        public static void main( String[] args ) {
            Section sect = new Section(30);

            sect.addStudent( new Student( "Kermit", 3 ) );
            sect.addStudent( new Student( "Big Bird", 12 ) );

            Student s = sect.findStudent(3);
            System.out.println( s.getName() );
        }
    }

  - This is very related to A0 - uses classes, arrays & loops

  - Discuss the program by walking through the main method.
      - Discuss constructors and when they get called. (When
          "new X" is used, space for X & its instance variables
          get created, & then the constructor is called.)
      - Discuss confusing things like the use of "++".
      - Mention the default values for instance variables:
          null for objects, 0 for ints and floats.
      - Explain how this line works.  A temporary variable doesn't
          help anything so it's not used.  Get used to this! :-)
          sect.addStudent( new Student( "Kermit", 3 ) );

  - Discuss why we want private instead of public instance variables
    in Student and Section.  (Among other things, that means that we
    can change how they are stored without affecting anyone else's
    code.)
  
  - Write the code for findStudent()
 
  - Now add a private static instance variable "numCreated" to class
    Student, and a public static method "incrementNumCreated" that
    does the obvious.  Call that method in the constructor.  Explain
    how there's only one copy of it, and we don't even need an
    instance to use it.  In the main method, add a call to
    Student.incrementNumCreated() to demonstrate this.
  
  - Use any remaining time to answer student questions.