CS U370 Assignment #2 
Section:  Clinger
Assigned:  Tuesday, 26 September 2006
Due:  Tuesday, 3 October 2006

The purpose of this assignment is:

 * To implement an algrebraic specification
 * To use packages in Java
 * To introduce enum types
 * To expose enum constants as part of a class's interface
 * To use java.util.Date
 * To implement the canonical methods equals() and toString()

You will complete an implementation in Java of the Issue class specified 
below. Collaboration between students is forbidden on this assignment.  
You are responsible for keeping your code hidden from all other students. 
Turn in your work on this assignment before 10 pm on the due date by sending 
electronic mail to:  will@ccs.neu.edu

with subject

    CSU370 assignment 2

and a body that consists of nothing but your Issue.java file.
That file should begin with a block comment that lists

    1.  Your name, as you want the instructor to write it.
    2.  Your email address.
    3.  Any remarks that you wish to make to the instructor.

Part of your grade will depend on the quality and correctness of your
code, part will depend on the readability of your code (comments and
indentation), and part will depend on your following the procedure above
for submitting your work.  Late assignments may be discounted, and very 
late assignments may be discarded.

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Note:  This assignment is based on the part of the Trac source
code and project management system that tracks issues (usually
bugs) within a software project.  For an example of Trac, you
can go to:

    http://larceny.ccs.neu.edu/trac/

Note: Issue.java must be part of the project package.

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Specification of the Issue class.

The Issue class shall be implemented in Java, and will be tested using 
Sun's Java 2 Runtime Environment, Standard Edition, version 5.0. The code 
for this implementation will be in the project package, and shall define 
a public class named Issue, which provides the following public methods, 
which are specified below.

Signature:

// Public constants, to be located within the Issue class.

public static enum Kind { DEFECT, ENHANCEMENT, ISSUE }
public static enum Status { NEW, ASSIGNED, CLOSED }
public static enum Priority { TRIVIAL, MINOR, MAJOR, CRITICAL }

// Creators, to be located within the Issue class.

public static Issue create(Kind, Status, Priority,
                           java.util.Date, String, String);
public static Issue create(Kind, String, String);
public static Issue create(String, String);

// Accessors

public Kind getKind();
public Status getStatus();
public Priority getPriority();
public java.util.Date getTargetDate();
public String getOwner();
public String getSummary();

// Predicates

public boolean isHigherPriorityThan(Issue)

// Canonical Methods

public String toString();


Specification of behavior:

Issue.create(k, s1, s2)
    = Issue.create(k, Issue.Status.NEW, Issue.Priority.MINOR, d, s1, s2)
    where d = current time + 180 days

Issue.create(s1, s2) = Issue.create(Issue.Kind.ISSUE, s1, s2)

Issue.create(k, stat, pri, d, s1, s2).getKind() = k
Issue.create(k, stat, pri, d, s1, s2).getStatus() = stat 
Issue.create(k, stat, pri, d, s1, s2).getPriority() = pri
Issue.create(k, stat, pri, d, s1, s2).getTargetDate() = d 
Issue.create(k, stat, pri, d, s1, s2).getOwner() = s1
Issue.create(k, stat, pri, d, s1, s2).getSummary() = s2 

Issue.create(k, stat, pri, d, s1, s2).isHigherPriorityThan(obj) = 
    true if pri.ordinal() > obj.getPriority().ordinal()
    false otherwise

Issue.create(k, stat, pri, d, s1, s2).toString() = 
    if a = Issue.Kind.DEFECT then
       "Issue: Defect: " + s2 + "  To be resolved by: " + d    
    if a = Issue.Kind.ENHANCEMENT then
       "Issue: Enhancement: " + s2 + "  To be resolved by: " + d
    otherwise
       "Issue: " + s2 + "  To be resolved by: " + d

Note 1: The owner and summary arguments to Issue.create() cannot be 
longer than 60 characters

Note 2: The java.util.Date argument to create must be later than the
time at which create is called.

If any of these conditions are violated, an IllegalArgumentException
should be thrown with an appropriate message.