Pattern Design Ultimate Design Pattern 2

Question 1

Which design pattern ensures that a class has only one instance and provides a global access point to it?

Accepted Answer

Singleton

Answer

The Singleton pattern restricts instantiation of a class to a single object and provides a global access point via a static method.

Question 2

The Template Method pattern defines a skeleton of an algorithm in a base class and lets subclasses override specific steps. What is the key mechanism used?

Accepted Answer

Inheritance and method overriding

Answer

Template Method relies on inheritance, where the base class defines the algorithm structure and subclasses override hook or abstract methods.

Question 3

Which pattern converts the interface of a class into another interface that clients expect, allowing incompatible interfaces to work together?

Accepted Answer

Adapter

Answer

The Adapter pattern wraps an existing class to make its interface compatible with a client's expected interface.

Question 4

In the Command pattern, what role does the 'Invoker' play?

Accepted Answer

Stores and executes command objects

Answer

The Invoker holds a command object and triggers its execute method, decoupling the sender from the receiver.

Question 5

Which structural pattern uses a tree structure to treat individual objects and compositions of objects uniformly?

Accepted Answer

Composite

Answer

The Composite pattern lets clients treat leaf nodes and composites the same way through a shared component interface.

Pattern Design Practice Test

Pattern Design Practice Test

Pattern Design Ultimate Design Pattern 2