Final

Question 1

used when we need to decouple an abstraction from its implementation so that the two can vary independently. This type of design pattern comes under structural pattern as this pattern decouples implementation class and abstract class by providing a bridge structure between them.

Answer 1

Bridge

Question 2

This pattern involves an interface which acts as a connection which makes the functionality of concrete classes independent from interface implementer classes. Both types of classes can be altered structurally without affecting each other.

Answer 2

Bridge

Question 3

behavioral software design pattern that implements a machine in an object -oriented way . is implemented by implementing each individual as a derived class of the interface , and implementing transitions by invoking methods defined by the pattern’s superclass

Answer 3

State design pattern

Question 4

can be interpreted as a strategy pattern which is able to switch the current strategy through invocations of methods defined in the pattern’s interface.

Answer 4

state pattern

Question 5

This pattern is used in computer programming to encapsulate varying behavior for the same object based on its internal state. This can be a cleaner way for an object to change its behavior at runtime without resorting to large monolithic conditional statements and thus improve maintainability

Answer 5

State design pattern

Question 6

is the degree of interdependence between software modules; a measure of how closely connected two routines or modules are; the strength of the relationships between modules.

Answer 6

coupling

Question 7

refers to the degree to which the elements of a module belong together. measures the strength of relationship between pieces of functionality within a given module.

Answer 7

Cohesion

Question 8

All good software design will go for HIGH __________ and LOW _________

Answer 8

cohesion
coupling

Question 9

We must have:
We want good:

Answer 9

Coupling
Coupling

Question 10

is used to describe just how much an outside class can get into another class’s members:

is used to describe just how much access an outside class has to another class with a well designed API:

Answer 10

Tight Coupling

Loose coupling

Question 11

is a principle of software development, aimed at reducing repetition of information of all kinds, especially useful in multi-tier architectures.

Answer 11

DRY

Question 12

Principles of object oriented design: SOLID

Answer 12

(SRP) Single responsibility principle
(OCP) Open Close Principle
(LSP) Liskov substitution principle
(ISP) Interface Segregation principle
(DIP) Dependency Inversion principle

Question 13

says “Every software module should have only one reason to change” Software Module Class, Function etc. Reason to change Responsibility

Answer 13

Single responsibility principle SRP

Question 14

says, “Software modules should be closed for modifications but open for extensions.”

Answer 14

Open close principle OCP

Question 15

says, “Subclasses should be substitutable for base classes.”

Answer 15

Liskov substitution principle LSP

Question 16

states that if a program module is using a Base class, then the reference to the Base class can be replaced with a Derived class without affecting the functionality of the program module .

Answer 16

Likov’s Substitution Principle

Question 17

states that a client should never be forced to implement an interface that it doesn’t use or clients shouldn’t be forced to depend on methods they do not use.

Answer 17

Interface segregation principle ISP

Question 18

says, “High level modules should not depend upon low level modules . Rather , both should depend upon abstractions .”

Answer 18

Dependency inversion principle DIP

Question 19

Entities must depend on abstractions not on concretions. It states that the high level module must not depend on the low level module, but they should depend on abstractions.

Answer 19

Dependency inversion principle DIP

Question 20

Who are the Gang of Four (GOF)

Answer 20

Erich Gamma
Richard Helm
Ralph Johnson
John Vlissides

Question 21

Elements of Reusable Object -Oriented

Answer 21

Design Patterns

Question 22

Software Defined original how many design patterns

Answer 22

23

Question 23

Creates an instance of several families of classes:

Separates object construction from its representation:

Creates an instance of several derived classes:

Avoid expensive acquisition and release of resources by recycling objects that are no longer in use:

A fully instance to be copied or cloned:

A class of which only a single instance can exist:

Answer 23

Abstract Factory
Builder
Factory method
Object Pool (Non GOF)
Prototype
Singleton

Question 24

Design patterns are about class instantiating:

Answer 24

Abstract factory
Builder
Factory method
Object pool
Prototype
Singleton

Question 25

Match interfaces of different classes:

Separates an object’s interface from its implementation:

A tree structure of simple and composite objects:

Add responsibilities to objects dynamically:

A single class that represents an entire subsystem:

A fine-grained instance used for efficient sharing:

Restricts accessor /mutator access:

An object representing another object:

Answer 25

Adapter
Bridge
Composite
Decorator
Facade
Flyweight
Private Class Data (Non -GOF )
Proxy

Question 26

Design pattern are all about class and object composition:

Answer 26

Adapter
Bridge
Composite
Decorator
Facade
Flyweight
Private Class Data (Non -GOF )
Proxy

Question 27

A way of passing a request between a chain of objects:

Encapsulate a command request as an object:

A way to include language elements in a program:

Sequentially access the elements of a collection:

Defines simplified communication between classes:

Capture and restore an object’s internal state:

Designed to act as a défault value of an object:

A way of notifying change to a number of classes:

Alter an object’s behavior when its state changes:

Encapsulates an algorithm inside a class:

Defer the exact steps of an algorithm to a subclass:

Defines a new operation to a class without change:

Answer 27

Chain of responsibility
Command
Interpreter
Iterator
Mediator
Memento
Null Object (Non-GOF )
Observer
State
Strategy
Template method
Visitor

Question 28

Design pattern are all about a class’s objects communication:

Answer 28

Chain of responsibility
Command
Interpreter
Iterator
Mediator
Memento
Null Object (Non-GOF )
Observer
State
Strategy
Template method
Visitor

Question 29

abstract the instantiation process. They help make a system independent of how its objects are created, composed, and represented. uses inheritance to vary the class that’s instantiated, whereas an object pattern will delegate instantiation to another object.

Answer 29

Creational design patterns

Question 30

Provide an interface for creating families of related or dependent objects without specifying their concrete classes.

Answer 30

Abstract Factory

Question 31

Separate the construction of a complex object from its representation so that the same construction process can create different representations.

Answer 31

Builder

Question 32

Define an interface for creating an object, but let subclasses decide which class to instantiate. lets a class defer instantiation to subclasses

Answer 32

Factory method

Question 33

Specify the kinds of objects to create using a prototypical instance , and create new objects by copying .

Answer 33

Prototype

Question 34

Ensure a class only has one instance, and provide a global point of access to it.

Answer 34

Singleton

Question 35

are concerned with how classes and objects are composed to form larger structures. use inheritance to compose interfaces or implementations . As a simple example, consider how multiple inheritance mixes two or more classes into one. The result is a class that combines the properties of its parent classes. This pattern is particularly useful for making independently developed class libraries work together.

Answer 35

Structural design patterns

Question 36

lets classes work together that couldn’t otherwise because of incompatible interfaces .

Answer 36

Adapter

Question 37

Decouple an abstraction from its implementation so that the two can vary independently

Answer 37

Bridge

Question 38

Compose objects into tree structures to represent part- whole hierarchies. lets clients treat individual objects and of objects uniformly

Answer 38

Composite

Question 39

Attach additional responsibilities to an object dynamically. provide a flexible alternative to subclassing for extending functionality.

Answer 39

Decorator

Question 40

Provide a unified interface to a set of interfaces in a subsystem . defines a higher-level interface that makes the subsystem easier to use.

Answer 40

Facade

Question 41

Use sharing to support large numbers of fine-grained objects efficiently

Answer 41

Flyweight

Question 42

Provide a surrogate or placeholder for another object to control access to it.

Answer 42

Proxy

Question 43

are concerned with algorithms and the assignment of responsibilities between objects. describe not just patterns of objects or classes but also the patterns of communication between them. These patterns characterize complex control flow that’s difficult to follow at run-time. They shift your focus away from flow of control to let you concentrate just on the way objects are interconnected.

Answer 43

Behavioral design patterns

Question 44

Avoid coupling the sender of a request to its receiver by giving more than one object a chance to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it.

Answer 44

Chain of responsibility

Question 45

Encapsulate a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations.

Answer 45

Command

Question 46

Given a language, define a representation for its grammar along that uses the representation to interpret sentences in the language

Answer 46

interpreter

Question 47

Provide a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

Answer 47

Iterator

Question 48

Define an object that encapsulates how a set of objects interact . promotes loose coupling by keeping objects from referring to each other explicitly, and it lets you vary their interaction independently

Answer 48

Mediator

Question 49

Without violating encapsulation, capture and externalize an object’s internal state so that the object can be restored to this state later.

Answer 49

Memento

Question 50

Define a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.

Answer 50

Observer

Question 51

Allow an object to alter its behavior when it’s internal state changes. The object will appear to change its class.

Answer 51

State

Question 52

Define a family of algorithms, encapsulate each one, and make them interchangeable. lets the algorithm vary independently from clients that use it.

Answer 52

Strategy

Question 53

Define the skeleton of an algorithm in an operation, deferring some steps to subclasses. lets subclasses redefine certain steps of an algorithm without changing the algorithm’s structure.

Answer 53

Template Method

Question 54

Represent an operation to be performed on the elements of an object structure. lets you define a new operation without changing the classes of the elements on which it operates.

Answer 54

Visitor