Test 2 Review

Logistics:

50 minute exam

Closed book / closed notes

No cheating / no make-up exam

Responsible for:

material in overheads

concepts discussed in class

OO concepts from all three programming assignments

Topics:

Object Oriented Paradigms

• Encapsulation
• Polymorphism , Dynamic Binding
• Inheritance (notion of classes that extend within a hierarchy)
• Interfaces (anywhere in hierarchy from which classes may implement)
• Hierarchies, Is-a and Has-a relationships

Subtypes

• Types and Subtypes
• Principle of Substitutability

Binding in Java

• References to objects
• Classes and subclasses (types and subtypes)
• Casting (explicit and implicit)

Cloning : Deep Copy vs  Shallow Copy

• Shallow copy concept
• Deep copy concept
• clone() method, overriding
• Semantic consistency of clone(), equals(), hashcode()
• interface Cloneable

Threads

• Thread concept
• Thread states and life cycle
• Thread creation in Java: extending Thread class vs implementing Runnable interface
• Starting a thread

• I/O Framework (we began covering this topic, but you're not responsible for this material yet)
• Byte Streams (not on this test)
• Character Streams: Reader / Writer (not on this test)

• On several occasions we've referred to the accessibility attributes table found in our text, and also in yellow in our class notes!  You are responsible for the information this table contains.
• We discussed the difference between equivalence and equality of objects.  You will be given true/false questions!  (but not the usual kind...)  Be prepared to evaluate boolean Java expressions that perform comparisons based on equivalence or equality.
• We discussed classes (types) and subclasses (subtypes) in the context of casting (implicit and explicit) and variable bindings for references to objects.  Be prepared to trace the execution of a small Java application with variables that bind to different types objects during the application's execution.
• We discussed cloning and the Cloneable interface.  Be prepared to trace the execution of a small Java application that involves a Cloneable object and cloning.
• Be sure you understand the concept of a Java application with multiple threads of execution. In the class notes, study the sample Java application that uses threads.  You'll be asked to trace possible executions of some very similar code.
• In assignment #2, we overrode the toString() method of class Object, which played a role in printing out the shapes we stored in a Vector.  You'll be asked a question about the need for casting while iterating through the shapes Vector and printing out the shapes.