Encapsulation vs Abstraction

Question

Here are the brief definitions of encapsulation and abstraction   Abstraction      The process of abstraction in Java is used to hide certain details and   only show the essential features of the object  In other words                  it deals with the outside view of an object  interface    The only good example i see for this  across different sites is   interface    Encapsulation      Its basically about hiding the state of object with the help of   modifiers like private public protected etc  we expose the state thru   public methods only if require    What we achieve with modifiers like private  public also hides unnecessary details from out side world which is nothing but also a abstraction concept  So  from above explanation looks like encapsulation is a part of abstraction or we can say it s a subset of abstraction  But why then encapsulation term is invented when we could deal it with abstraction only  I am sure there should be some major difference which distinguishes them but most of material on net says almost same thing for both of them   Though this question has been raised on this forum earlier too but I am posting it again with specific doubts  Some replies also says abstraction is a concept and encapsulation is implementation  But I don t buy this - If it is true  then I can think these two different concepts are provided to confuse us   Update - After 5 years i have come up with my own answer whichs is the gist based on answers in this post and below ones   difference between abstraction and encapsulation  encapsulation vs abstraction real world example

User · Answer

Lets try to understand in a different way.

What may happen if Abstraction is not there and What may happen if Encapsulation is not there.

If Abstraction is not there, then you can say the object is use less. You cannot identify the object nor can you access any functionality of it. Take a example of a TV, if you do not have an option to power on, change channel, increase or decrease volume etc., then what's the use of TV and how do you use it ?

If Encapsulation is not there or not being implemented properly, then you may misuse the object. There by data/components may get misused. Take the same example of TV, If there is no encapsulation done to the volume of TV, then the volume controller may be misused by making it come below or go beyond its limit (0-40/50).

User · Answer

in a simple sentence  I cay say  The essence of abstraction is to extract essential properties while omitting inessential details  But why should we omit inessential details  The key motivator is preventing the risk of change  You might consider abstraction is same as encapsulation  But encapsulation means the act of enclosing one or more items within a container  not hiding details  If you make the argument that  everything that was encapsulated was also hidden   This is obviously not true  For example  even though information may be encapsulated within record structures and arrays  this information is usually not hidden  unless hidden via some other mechanism

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Abstraction is the concept of describing something in simpler terms  i e abstracting away the details  in order to focus on what is important  This is also seen in abstract art  for example  where the artist focuses on the building blocks of images  such as colour or shapes    The same idea translates to OOP by using an inheritance hierarchy  where more abstract concepts are at the top and more concrete ideas  at the bottom  build upon their abstractions   At its most abstract level there is no implementation details at all and perhaps very few commonalities  which are added as the abstraction decreases   As an example  at the top might be an interface with a single method  then the next level  provides several abstract classes  which may or may not fill in some of the details about the top level  but branches by adding their own abstract methods  then for each of these abstract classes are concrete classes providing implementations of all the remaining methods   Encapsulation is a technique   It may or may not be for aiding in abstraction  but it is certainly about information hiding and or organisation  It demands data and functions be grouped in some way - of course good OOP practice demands that they should be grouped by abstraction   However  there are other uses which just aid in maintainability etc

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Encapsulation - the process of hiding components of the class to prevent direct access from the outside  It is achieved by using  private  modifier to prevent direct access to some class members  data field or method  from other classes or objects meanwhile providing access to these private members by public members  Interface   That make the class members protected as human organs hidden encapsulated under the skin or some shield   Abstraction - A principle must be followed in writing OOP program that say  you must include in the class only components that are interesting in the task of the program   For example  the object student has a lot of characters as a human  name  age  weight  hair color  eye color  etc  But  when you create a class in OOP to work with students you should include only those characters that really matter for student database  name  age  specialty  level  marks     etc  in C   you can create abstract class by using the modifier  virtual  with any methods in the class and that will make it unusable in direct but you can derive other classes from it and create implementation for its members with adding required members based on the task

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encapsulation is a part of abstraction or we can say its a subset of   abstraction   They are different concepts      Abstraction is the process of refining away all the unneeded unimportant attributes of an object and keep only the characteristics best suitable for your domain     E g  for a person  you decide to keep first and last name and SSN  Age  height  weight etc are ignored as irrelevant     Abstraction is where your design starts  Encapsulation is the next step where it recognizes operations suitable on the attributes you accepted to keep during the abstraction process  It is the association of the data with the operation that act upon them  I e  data and methods are bundled together

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Encapsulation is a strategy used as part of abstraction  Encapsulation refers to the state of objects - objects encapsulate their state and hide it from the outside  outside users of the class interact with it through its methods  but cannot access the classes state directly  So the class abstracts away the implementation details related to its state   Abstraction is a more generic term  it can also be achieved by  amongst others  subclassing  For example  the interface List in the standard library is an abstraction for a sequence of items  indexed by their position  concrete examples of a List are an ArrayList or a LinkedList  Code that interacts with a List abstracts over the detail of which kind of a list it is using   Abstraction is often not possible without hiding underlying state by encapsulation - if a class exposes its internal state  it can t change its inner workings  and thus cannot be abstracted

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Encapsulation protects to collapse the internal behaviour of object instance from external entity  So  a control should be provided to confirm that the data which is being supplied is not going to harm the internal system of instance object to survive its existance   Good example  Divider is a class which has two instance variable dividend and divisor and a method getDividedValue   Can you please think  if the divisor is set to 0 then internal system behaviour  getDivided   will break   So  the object internal behaviour could be protected by throwing exception through a method

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Answering my own question after 5 years as i feel it still need more details  Abstraction   Technical Definition  - Abstraction is a concept to hide unnecessary details complex or simple  and only show the essential features of the object  There is no implementaion here its just an concept  What it means practically - When i say my company needs some medium device so that employees can connect to customer   This is the purest form of abstaction like interface in java  as that device medium can be phone or internet or skype or in person or email etc  I am not going into nitty gritty of device medium  Even when i say my company needs some medium device so that employees can connect to customer through voice call  Then also i am talking abstract but at bit lower level as device medium can be phone or skype or something else etc  Now when i say my company needs some phone so that employees can connect to customer through voice call  Then also i am talking abstract but at bit lower level as phone can be of  any company like iphone or samsung or nokia etc  Encapsulation - Its basically about hiding the state information  of object with the help of modifiers like private public protected etc  we expose the state thru public methods only if require   What it means practically -  Now when i say my company needs some iphone so that employees can connect to customer through voice call Now i am talking about some concrete object like iphone   Even though i am not going into nitty gritty of iphone here too but iphone has some state concrecrete info implementation associated with it where device medium does not have  When i say concrete object  actually it means any object which has some not complete like java abstract class  implementation info associated with it    So iphone actually used here encapsulation as strategy to hide its  state information and expose only the ones which it think  should be exposed  So both abstraction and encapsulation hides some unnecessary details but abstraction at the concept level and encapsulation actually at implementation level  This is the gist based on answers in this post and below ones   difference between abstraction and encapsulation  encapsulation vs abstraction real world example

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NOTE  I am sharing this  It is not mean that here is not good answer but because I easily understood   Answer   When a class is conceptualized  what are the properties we can have in it given the context  If we are designing a class Animal in the context of a zoo  it is important that we have an attribute as animalType to describe domestic or wild  This attribute may not make sense when we design the class in a different context   Similarly  what are the behaviors we are going to have in the class  Abstraction is also applied here  What is necessary to have here and what will be an overdose  Then we cut off some information from the class  This process is applying abstraction   When we ask for difference between encapsulation and abstraction  I would say  encapsulation uses abstraction as a concept  So then  is it only encapsulation  No  abstraction is even a concept applied as part of inheritance and polymorphism   Go here for more explanation about this topic

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Encapsulation is hiding unnecessary data in a capsule or unit  Abstraction is showing essential feature of an object  Encapsulation is used to hide its member from outside class and interface Using access modifiers provided in c  like public private protected etc  example   Class Learn     private int a             by making it private we are hiding it from other   private void show       class to access it        console writeline a           Here we have wrap data in a unit or capsule i e Class      Abstraction is just opposite of Encapsulation    Abstraction is used to show important and relevant data to user  best real world example In a mobile phone  you see their different types of functionalities as camera  mp3 player  calling function  recording function  multimedia etc  It is abstraction  because you are seeing only relevant information instead of their internal engineering    abstract class MobilePhone               public void Calling            put necessary or essential data         public void SendSMS            calling n sms are main in mobile            public class BlackBerry   MobilePhone      inherited main feature               public void FMRadio                 added new         public void MP3            public void Camera            public void Recording

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Abstraction is a very general term  and abstraction in software is not limited to object-oriented languages  A dictionary definition   the act of considering something as a general quality or characteristic  apart from concrete realities  specific objects  or actual instances    Assembly language can be thought of as an abstraction of machine code -- assembly expresses the essential details and structure of the machine code  but frees you from having to think about the opcodes used  the layout of the code in memory  making jumps go to the right address  etc   Your operating system s API is an abstraction of the underlying machine  Your compiler provides a layer of abstraction which shields you from the details of assembly language  The TCP IP stack built into your operating system abstracts away the details of transmitting bits over a network  If you go down all the way to the raw silicon  the people who designed your CPU did so using circuit diagrams written in terms of  diodes  and  transistors   which are abstractions of how electrons travel through semiconductor crystals   In software  everything is an abstraction  We build programs which simulate or model some aspect of reality  but by necessity our models always abstract away some details of the  real thing   We build layer on layer on layer of abstractions  because it is the only way we get anything done   Imagine you were trying to make  say  a sudoku solver  and you had to design it using only semiconductor crystals   OK  I need a piece of N-type silicon here       In comparison   encapsulation  is a very specific and limited term  Some of the other answers to this question have already given good definitions for it

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This is how I understood it   In Object oriented programming  we have something called classes  What are they for  They are to store some state and to store some methods to change that state i e   they are encapsulating state and its methods    It class  does not care about the visibility of its own or of its contents  If we choose to hide the state or some methods  it is information hiding   Now  take the scenario of an inheritance  We have a base class and a couple of derived  inherited  classes  So  what is the base class doing here  It is abstracting out some things from the derived classes   All of them are different  right  But  we mix them up to write good object oriented programs  Hope it helps

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Abstraction delineates a context-specific  simplified representation of something  it ignores contextually-irrelevant details and includes contextually-important details   Encapsulation restricts outside access to something s parts and bundles that thing s state with the procedures that use the state     Take people  for instance  In the context of surgery a useful abstraction ignores a person s religious beliefs and includes the person s body  Further  people encapsulate their memories with the thought processes that use those memories  An abstraction need not have encapsulation  for instance  a painting of a person neither hides its parts nor bundles procedures with its state  And  encapsulation need not have an associated abstraction  for instance  real people  not abstract ones  encapsulate their organs with their metabolism

[java] Encapsulation vs Abstraction?

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