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Design Pattern Interview Questions and Thesaurus




What are design patterns

Design patterns are recurring solution to recurring problems in software architecture. According to Gang Of Four, there are three types of Design Pattern

1. Creational
2. Structural
3. Behavioral

Creational Design Pattern

Abstract Factory – Creates an instance of several families of classes
Builder – Separates object construction from its representation
Factory Method – Creates an instance of several derived classes
Prototype – A fully initialized instance to be copied or cloned
Singleton – A class of which only a single instance can exist

Structural Design Pattern

Adapter – Match interfaces of different classes
Bridge – Separates an object’s interface from its implementation
Composite – A tree structure of simple and composite objects
Decorator – Add responsibilities to objects dynamically
Facade – A single class that represents an entire subsystem
Flyweight – A fine-grained instance used for efficient sharing
Proxy – An object representing another object

Behavioral Design Pattern

Chain of Resp. – A way of passing a request between a chain of objects
Command – Encapsulate a command request as an object
Interpreter – A way to include language elements in a program
Iterator – Sequentially access the elements of a collection
Mediator – Defines simplified communication between classes
Memento – Capture and restore an object’s internal state
Observer – A way of notifying change to a number of classes
State – Alter an object’s behavior when its state changes
Strategy – Encapsulates an algorithm inside a class
Template Method – Defer the exact steps of an algorithm to a subclass
Visitor – Defines a new operation to a class without change