* Using a data structure to represent a set

* Writing and using a checked exception

* Extending the Exception class

What should you upload via Blackboard?

The files, SET.java, OrderedPair.java, and OrderedPairException.java.

   The current version of SET.java contains compiler errors that should be resolved asyou write the code for this project.

Coding Standards

*At most one return in each method

* Do not use the break, continue or goto keywords

* Write comments for any method you write

* If the main method generates an OrderedPairException then display the message returned by the getMessage method.

* Use try-catch blocks to catch exceptions in the main method.

* Test your code by using the SET.java file posted online.

PART1:

Write a class with the header

public class OrderedPair>

implements Comparable>

instance variables

private Key x

private Key y

constructor

publicOrderedPair(Key x, Key y) // initialize the instance variables

methods

(i) accessor and mutator methods for the instance variables.

(ii) publicintcompareTo(OrderedPair s)

if (this.x  is not equal to s.x) then return x.compareTo(s.x)

else return y.compareTo(s.y)

(iii)  public String toString() - returns a String that represents x and y as an ordered pair.  For instance, if x = "cat " and y = "dog ", then this method returns  the String, "(cat , dog ) ". 

PART2

A class with the header

public class OrderedPairException extends Exception

This class has a constructor with the following header

publicOrderedPairException(String msg)

The only statement in this constructor uses the parameter, msg, to invoke the constructor in the Exception class.

PART3:

Add the following methods to the SET class

public SET difference(SETst)

Returns the complement of this set with the set object represented by the parameter,

st.  (In order words, return this - st)

public void display()

Displays the contents of this set. Use the toString method to display each element in the set.  If the set is null or it's empty then display "Empty Set".

public SetorderedPairs(SETst) throws OrderedPairedException

Returns a set consisting of the ordered pairs in this set and the set represented by the parameter, st.

If this set is null or it's empty then throw an OrderedPairException that contains the message "First Coordinate Set is Null".

If the set represented by the parameter st is null or it's empty then throw an

OrderedPairException that contains the message "Second Coordinate Set is Null".

Example  if c = {"A", "B", and "C"} and d = {"X", "Y"}  then the set of order pairs is

{ ("A", "X"), ("A", "Y"), ("B", "X"), ("B", "Y"), ("C", "X"), ("C", "Y") }