Pattern Design Design Pattern 3

Question 1

How does the Strategy pattern differ from the State pattern even though both change an object's behavior at runtime?

Accepted Answer

Strategy encapsulates interchangeable algorithms chosen by the client; State encapsulates behavior tied to internal state transitions

Answer

Strategy lets clients choose among interchangeable algorithms, while State manages behavior changes driven by the object's own internal state machine.

Question 2

What is the primary intent of the Composite pattern?

Accepted Answer

Treat individual objects and compositions of objects uniformly through a common interface

Answer

Composite lets clients treat single leaf objects and composite tree structures identically through a shared component interface.

Question 3

Which behavioral pattern decouples the sender of a request from its receiver by passing the request along a chain of handlers?

Accepted Answer

Chain of Responsibility

Answer

Chain of Responsibility passes a request along a chain of potential handlers, each deciding whether to handle it or forward it.

Question 4

In the Proxy pattern, which variant is used to defer the creation of an expensive object until it is actually needed?

Accepted Answer

Virtual Proxy

Answer

A Virtual Proxy delays creation and initialization of an expensive object until a client first requests it.

Question 5

A team wants to log every method call on a database connection without modifying the connection class. Which pattern is most appropriate?

Accepted Answer

Decorator

Answer

Decorator wraps the existing object and adds logging behavior transparently, without altering the original class.

Pattern Design Practice Test

Pattern Design Practice Test

Pattern Design Design Pattern 3