Encapsulation vs Abstraction?
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
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.
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.
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.
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();
}
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