C# FAQ: abstract class & interface , private constructor
What is abstract class ?
Abstract class is a base class or a parent class. Abstract classes can have empty abstract methods or it can have implemented methods which can be overridden by child classes.
The next question i expected was on interfaces and yes there it comes.
What are interfaces?
Interface is a contract class with empty methods , properties and functions. Any class which implements the interface has to compulsory implement all the empty methods , functions and properties of the interface.
Now the 1000% sure question was bound to come difference between them...
What's the difference between abstract class and interface?
There are many differences, below are some key two differences :-
Can we create a object of abstract class or interface?
No we can not.
Now the practical question..
In what scenarios will you use a abstract class and in what scenarios will you use a interface?
If you want to increase reusability in inheritance then abstract classes are good. If you want implement or force some methods across classes must be for uniformity you can use a interface. So to increase reusability via inheritance use abstract class as it is nothing but a base class and to force methods use interfaces.
-- We can not create a object of the class.
-- We can not inherit the class.
When to use private contstructor ==> when we have some classes like Utilty or Helper Classes Which we referer multiple places and we dont want to create instance of it all the time we call it. only one instance of such class will be used all over the project.
Abstract class is a base class or a parent class. Abstract classes can have empty abstract methods or it can have implemented methods which can be overridden by child classes.
The next question i expected was on interfaces and yes there it comes.
What are interfaces?
Interface is a contract class with empty methods , properties and functions. Any class which implements the interface has to compulsory implement all the empty methods , functions and properties of the interface.
Now the 1000% sure question was bound to come difference between them...
What's the difference between abstract class and interface?
There are many differences, below are some key two differences :-
- Abstract class are base class or parent class while interfaces are contracts.
- Abstract class can have some implemented methods and functions while interfaces methods and functions are completely empty.
- Abstract classes are inherited while interfaces are implemented.
- Abstract classes are used when we want to increase reusability in inheritance while interfaces are used to force a contract.
Can we create a object of abstract class or interface?
No we can not.
Now the practical question..
In what scenarios will you use a abstract class and in what scenarios will you use a interface?
If you want to increase reusability in inheritance then abstract classes are good. If you want implement or force some methods across classes must be for uniformity you can use a interface. So to increase reusability via inheritance use abstract class as it is nothing but a base class and to force methods use interfaces.
When we declare a class constructor as private , we can not do 2 things:-
-- We can not create a object of the class.
-- We can not inherit the class.
When to use private contstructor ==> when we have some classes like Utilty or Helper Classes Which we referer multiple places and we dont want to create instance of it all the time we call it. only one instance of such class will be used all over the project.
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