Design Patterns Interview questions
Design patterns are more related to the design level approach to a problem than coding level . Design pattern interview questions frequently asked in more experienced level of interviews. I have listed out most of them below please add as comment missed out questions.
Design patterns are more related to the design level approach to a problem than coding level . Design pattern interview questions frequently asked in more experienced level of interviews. I have listed out most of them below please add as comment missed out questions.
Q) What are Design Patterns ? (Design
patterns interview questions -1)
Design patterns are more
general solution for a frequently occurring problem with in a
software design . Design patterns are time tested practices for
Object Oriented Programming .It help people to think Object Oriented
aspect of thinking .
Q) What are the main types of design
patterns ? (Design Patterns interview questions -2)
It mainly classifieds as
three categories Creationals , structural and Behavioral patterns
Creational Patterns : It deals with the
object creational mechanisms. It used in situations like its basic
form of object creation increases the complexity of code base. It is
mainly deals with the way of creating objects. The types of
creational patterns are
- Abstract factory patterns
- Builder patterns
- Factory method patterns
- Prototype patterns
- Singleton patterns
Structural Patterns : The structural
patterns are design patterns that ease the design by identifying the
exact relationship with entities. In other words, it deals with how
the objects and classes can be composed ,to form larger structures.
The types of structural patterns are
- Adapter patterns
- Bridge patterns
- Composite patterns
- Decorator patterns
- Facade patterns
- Flyweight patterns
- Proxy patterns
Behavioral Patterns : It is concerned
with assignment of responsibilities between objects. It describes how
the objects interact . It explains how the objects and classed
interact to make things happens and how its tasks are divided to them.
- Chain of responsibility pattern
- Command pattern
- Interpreter pattern
- Iterator pattern
- Mediator pattern
- Memento pattern
- Observer pattern
- State pattern
- Strategy pattern
- Template pattern
- Visitor pattern
Q)What are factory patterns in Design
patterns ? (Design patterns interview question -3)
Factory pattern is included among most used design patterns . It falls under creational design
patterns. We create object without exposing creational logic . We
use interface to create object and let the subclass really describes
which class to instantiate .
Q)What is Abstract factory pattern ?(Design patterns interview question -4)
Abstract factory patterns acts as
a super factory which create another factories.This is also known as
factory of factory classes. In this interface is responsible for
creating a set of related objects .
Q) What is a singleton Class ? (Design
patterns interview question -5)
Singleton pattern is the
simplest form of design pattern . It comes under the creational
design pattern. It is used where we need to create only one instance
of a class and provides global point of access to it. Weather it may
be DB connection or other project constant etc. The idea is this
class should be instantiated only once .
Q)What is Facade Pattern (Design
pattern interview question -6)
Facade patterns comes under Structural Pattern . It uses when the system is very complex to
implement .when it has number of independent classes or source code
of some dll is not available. Facade patterns mask the complexity and
create an interface which is easy to implement . This contains a
single wrapper class which contains only the necessary set of members
.
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