Name __________________________________________
The following might be names of patterns:! Abstract Class, Abstract Factory, Adapter, Bridge, Builder,
Chain of Responsibility, Client, Collaborator, Command, Command Processor, Composite, Context,
Decorator, Façade, Factory Method, Flyweight, Interpreter, Mediator, Memento, Observer, Prototype,
Proxy, Singleton, Specification, State, Strategy, Template Method, Visitor.
The purpose of many of the design patterns is to make it easy to change some property of the
system.!In the first 7 problems give one pattern even if more than one pattern may apply.
1. (3 points) What design pattern would you use to make it easy to change the way a set of objects
interact with each other.
2. (3 points) What design pattern would you use to make it easy to change the implementation of an
abstraction.
3. (3 points) What design pattern would you use when you change the internal state of an object, but
you want to be able to remember this state and then later tell the object to go back to that state.
4. (3 points) What design pattern would you use when you need to evaluate an expression in a small
language.
5. (3 points) What design pattern would you use when you want to reduce the coupling between
classes.
6. (3 points) What design pattern should you think of when you want to hide how you construct a
complex object?.
Suppose you were designing the file system of an operating system.
7. (3 points) Your file system has many classes in it, but you want to hide them from the application
programmers and present a simpler interface to them.! What design pattern lets you hide the
complexity of a subsystem like a file system?
8. (10 points) Proxy and Strategy are similar because they both contain multiple nested classes.! In
other respects, they are quite different.! Explain the differences between Proxy and Strategy.
5/14/09"CS 635 Final"Page 1 of 2
