SWE 619 Assignment 10
Spring 2013

Goal: The contract for equals().

As it happens, Liskov's discussion of equals() for the Point2 and Point3 classes (see section 7.9.3, page 182) is wrong.

• Implement enough of Point2 and Point3 that you can instantiate Point2 and Point3 objects.
• Identify exactly which part of the equals() contract is violated.
• Implement a class NewPoint3 that has a Point2 object as an instance variable (that is, use composition instead of inheritance.)
• Override equals() and hashCode() for both Point2 and NewPoint3. Use Bloch's recipe.
• Provide 2 JUnit tests to document that:
  • equals() violates its contract for the Point2, Point3 combination.
  • The property violated in the previous test is satisfied for the Point2, NewPoint3 combination.