Pattern Design Behavioral Design Patterns

Question 1

Which behavioral pattern defines a one-to-many dependency so that when one object changes state, all dependents are notified automatically?

Accepted Answer

Observer

Answer

The Observer pattern establishes a subscription mechanism that notifies all registered observers whenever the subject's state changes.

Question 2

The Strategy pattern allows:

Accepted Answer

Swapping algorithms at runtime without changing the client

Answer

Strategy defines a family of algorithms, encapsulates each one, and makes them interchangeable so the client can select the appropriate algorithm at runtime.

Question 3

The Command pattern encapsulates a request as an object primarily to support:

Accepted Answer

Undo/redo, queuing, and logging of operations

Answer

By encapsulating requests as Command objects, you can queue them, log them, and reverse them with an undo operation.

Question 4

Template Method pattern enforces an algorithm's structure by:

Accepted Answer

Defining the skeleton in a base class with some steps deferred to subclasses

Answer

Template Method defines the overall algorithm in the parent class and lets subclasses override specific steps without changing the algorithm's structure.

Question 5

Which behavioral pattern is used to traverse elements of a collection without exposing the underlying representation?

Accepted Answer

Iterator

Answer

The Iterator pattern provides a standard way to access elements of a collection sequentially without needing to know its internal structure.

Pattern Design Practice Test

Pattern Design Practice Test

Pattern Design Behavioral Design Patterns