Pattern Design Basic Design Pattern 4

Question 1

What is the key difference between the Strategy and Template Method patterns?

Accepted Answer

Strategy changes the whole algorithm; Template Method changes only steps

Answer

Strategy replaces an entire algorithm via composition, while Template Method fixes the algorithm's skeleton in a base class and lets subclasses override individual steps.

Question 2

The Chain of Responsibility pattern is most appropriate when:

Accepted Answer

Multiple objects may handle a request and the handler isn't known a priori

Answer

Chain of Responsibility passes a request along a chain of handlers until one processes it, decoupling senders from receivers.

Question 3

Which pattern provides a way to access elements of an aggregate object sequentially without exposing its internal representation?

Accepted Answer

Iterator

Answer

The Iterator pattern abstracts traversal logic into an iterator object, so clients can loop over a collection without knowing its underlying structure.

Question 4

In the Mediator pattern, what role does the mediator object play?

Accepted Answer

It centralizes communication between colleague objects

Answer

The Mediator encapsulates how a set of objects interact, promoting loose coupling by keeping objects from referring to each other directly.

Question 5

What is the intent of the Memento pattern?

Accepted Answer

Capture and externalize an object's state so it can be restored later

Answer

The Memento pattern saves a snapshot of an object's internal state outside the object so it can be restored to that state later without violating encapsulation.

Pattern Design Practice Test

Pattern Design Practice Test

Pattern Design Basic Design Pattern 4