CpSc 210, Section 1
                             Assignment 2 
                          September 25, 2001 


Due:  Wednesday, October 3  at 11:59 p.m.  

Assignment:  Implementing a class Set


Total point value of assignment:  100 points
Not accepted late.

This assignment is to be done INDIVIDUALLY.

Assignment:  Design and implement a class, Set, which must be stored in a
     file named Set.java.  (Failure to name file or class correctly is an
     automatic 20 point deduction.)  Mathematically, a set is a collection
     of objects without duplicates and without order (so we shall not
     allow the compareTo method to be used on items in a Set).

     The Set is to be implemented using a Vector as instance variable
     to hold the elements of the Set.  The following methods are required.

     public Set ( )
     // Default constructor, constructs an empty Set

     public void addItem ( Object item )
     // Pre:  item is not null
     // Post:  If item is not in this Set, item is added to this Set.
     //        If item is already in this Set, this Set remains unchanged.

     public boolean contains ( Object item )
     // Pre:  item is not null
     // Post:  returns true if item is in Set.  Otherwise, returns false.

     public boolean isEmpty ( )
     // Post:  returns true if this Set is empty.  Otherwise, returns false.

     public void removeItem ( Object item )
     // Pre:  item is in this Set
     // Post:  item has been removed from this Set

     public int size ( )
     // Post:  returns the number of items in this Set

     public String toString ( )
     // Post:  returns String representation of Set in the form

     public boolean equals ( Object other )
     // Pre:  other is not null
     // Post:  returns true if this and other contain the same collection
     //        of Objects.  Otherwise, returns false.

     public Set union ( Set other )
     // Pre:  other is a Set and is not null (other may be empty)
     // Post:  returns the union of Sets this and other

     public Set intersection ( Set other )
     // Pre:  other is a Set and is not null (other may be empty)
     // Post:  returns the intersection of Sets this and other

     You may include any additional methods you need.  Additional methods
     should be private instead of public.


 	Sample results are:
	Let A = { 1, 2, 3, 4 }, let B = { 5, 6, 7 }, and let C = { 4, 5 },
         the size of Set A is 4, the size of Set B is 3, and the size of C is 2
         A union B is { 1, 2, 3, 4, 5, 6, 7 }
         A union C is { 1, 2, 3, 4, 5 }
         A intersect B is the empty set
         A intersect C is { 4 }


Grading Rubric:

	10 pts. reasonable attempt to solve problem as assigned
	10 pts. also compiles
	10 pts. style standards (includes clarity)

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