Advantages of abstraction

Question

Hello I have a question about abstraction. I just finished reading OOPS Concepts and .NET Part 2: Inheritance, Abstraction, & Polymorphism which was a really good article and very helpful start to OOP capabilities but I still don’t understand the advantages of abstraction. For example, say I have a parent class called A with an abstract method getInfo(). Say the Class A has 2 child classes called B and C. Both B and C have an overridden method called GetInfo().// code in blue The code in orange doesnt have abstraction, just 2 classes B and C inheiting a property form parent class A. so my question is why the code in blue better than the code in orange, in other words what is the advantages of abstraction. Class A _property1; getInfo() //abstract method Class B Class C getInfo() //override method getInfo() //override method Class A _property1; Class B Class C GetB() //just another function which has the same code as ClassB.getInfo() GetC() //just another function which has the same code as ClassC.getInfo() Thanks in adavance and i hope that my question makes sense

Rajanikant Hawaldar · Answer

HI Yasmine, Advantage is abstracting(making comman) properties and method of derived classes in base class and an abstract class is an incomplete class or special class we can't be instantiated. The purpose of an abstract class is to provide a blueprint for derived classes and set some rules what the derived classes must implement when they inherit an abstract class. We can use an abstract class as a base class and all derived classes must implement abstract definitions.An abstract method must be implemented in all non-abstract classes using the override keyword. After overriding the abstract method is in the non-Abstract class. We can derive this class in another class and again we can override the same abstract method with it.

Bhoomi Parekh · Answer

Hi, It is not for interface and an abstract class. The Abstract class and Normal Class. Why anyone should use an abstract class rather than the normal class? Btw I found the answer - By using abstract class you can provide a common definition of base class to multiple child class. You can combine several related classes together as siblings. Thanks

Gajendra Jangid · Answer

'll see if I can do this with generic terminology without too much hand-waving. An interface is like a contract. It says that a class which implements the interface agrees to implement all of the functions declared (as signatures only; no function definition) by that interface. The class may do so in any way it chooses, and provide any other functionality, as long as it implements each one of the declared functions. An interface is useful when you want to be able to use some common functionality of otherwise unrelated classes- they share no implementation details, only the function signatures. In C#, function declarations within an interface are implicitly pure virtual. An abstract class is a partially defined class that cannot be instantiated. It (usually) includes some implementation, but leaves some functions as pure virtual- declared only by their signature. Pure virtual functions are not defined in the class that declares them, so they must be implemented by a subclass (unless it too is an abstract class). Only a subclass which defines all of the pure virtual functions can be instantiated. The purpose of an abstract class is to define some common behavior that can be inherited by multiple subclasses, without implementing the entire class. In C#, the abstract keyword designates both an abstract class and a pure virtual method. In practical terms, the difference between the two is that an interface defines only pure virtual functions, while an abstract class may also include concrete functions, members, or any other aspect of a class.

Bhoomi Parekh · Answer

Hi, I have the same question. If we use a simple class or an abstract class. What is the exact difference between them? What is the advantage of abstract class over the normal class?

Sunny Chen · Answer

I suggest you read Design Patterns along with your studying. This will much help on your understanding of abstraction, interfaces, overriding and other OOAD concepts. Thanks!

Mahesh Chand · Answer

Abstraction in OOP is used by advanced designers and architects when they design their class libraries that may be used by some developers and used to enforce some design rules. If you have a class library and you want to make sure the users of that class library must inherite a class and must override some methods before they can even use the library. By enforcing this rule, you may be doing login in this class ( say initialization of some engine defined ), your class library makes sure it has what it needs to execute next peice of code. Here is a detailed reading on abstract classes: Abstract Classes And Methods This is a detailed analysis of Abstract classes and methods in C# with some ... The keyword abstract can be used with both classes and methods in C# to ...

Yasmine Amin · Answer

Thank you khan for your reply but i still dont get the advantage of abstraction. i mean in the example you mentioned u can use inheritance why would use abstraction too??? i mean whats the point of declaring some method in a base class abstract that has no code in it and then inherit that method in a sub class and then have the code there.. i just dont see the point in inheriting something thats empty and cannot be instantiated.. i mean the abstract method is totally useless so why write the extra code. thanks again

Arshad · Answer

Hi, well we know that we cant create the object of abstract class but it has to be Inherite,I will tell you one real time Example like a bank account. People can have savings accounts, checking accounts, credit accounts, investment accounts, but not the generic bank accounts. In this case, bank account can be an abstract class and all the other specialized bank accounts inherit from bank account, thats all Thanks