Showing posts with label OOPS. Show all posts
Showing posts with label OOPS. Show all posts
frequently asked OOPS Interview Question and Answer
frequently asked OOPS Interview Question and Answer
What is object-oriented programming (OOP)?
OOP is a technique to develop logical modules, such as classes that contain properties, methods, fields, and events. An object is created in the program to represent a class. Therefore, an object encapsulates all the features, such as data and behavior that are associated to a class. OOP allows developers to develop modular programs and assemble them as software. Objects are used to access data and behaviors of different software modules, such as classes, namespaces, and sharable assemblies. .NET Framework supports only OOP languages, such as Visual Basic .NET, Visual C#, and Visual C++.
How can prevent your class to be inherited further?
You can prevent a class from being inherited further by defining it with the sealed keyword.
When we will use an Interface and Abstract class?
Use an abstract class
When creating a class library which will be widely distributed or reused—especially to clients, use an abstract class in preference to an interface; because, it simplifies versioning. This is the practice used by the Microsoft team which developed the Base Class Library. ( COM was designed around interfaces.)
Use an abstract class to define a common base class for a family of types.
Use an abstract class to provide default behavior.
Subclass only a base class in a hierarchy to which the class logically belongs.
Use an interface
When creating a standalone project which can be changed at will, use an interface in preference to an abstract class; because, it offers more design flexibility.
Use interfaces to introduce polymorphic behavior without subclassing and to model multiple inheritance—allowing a specific type to support numerous behaviors.
Use an interface to design a polymorphic hierarchy for value types.
Use an interface when an immutable contract is really intended.
A well-designed interface defines a very specific range of functionality. Split up interfaces that contain unrelated functionality.
When creating a class library which will be widely distributed or reused—especially to clients, use an abstract class in preference to an interface; because, it simplifies versioning. This is the practice used by the Microsoft team which developed the Base Class Library. ( COM was designed around interfaces.)
Use an abstract class to define a common base class for a family of types.
Use an abstract class to provide default behavior.
Subclass only a base class in a hierarchy to which the class logically belongs.
Use an interface
When creating a standalone project which can be changed at will, use an interface in preference to an abstract class; because, it offers more design flexibility.
Use interfaces to introduce polymorphic behavior without subclassing and to model multiple inheritance—allowing a specific type to support numerous behaviors.
Use an interface to design a polymorphic hierarchy for value types.
Use an interface when an immutable contract is really intended.
A well-designed interface defines a very specific range of functionality. Split up interfaces that contain unrelated functionality.
What is Static Class in .Net?
Static classes are used when a class provides functionality that is not specific to any unique instance. Here are the features of static classes in C# 2.0.
Static classes can not be instantiated.
Static classes are sealed so they can not be inherited.
Only static members are allowed.
Static classes can only have static constructor to initialize static members.
Advantages
Compiler makes sure that no instance of static class is created. In previous version of C#, the constructor has to be marked private to avoid this from happening.
Also compiler makes sure that no instance members are declared within a static class.
Static classes can not be instantiated.
Static classes are sealed so they can not be inherited.
Only static members are allowed.
Static classes can only have static constructor to initialize static members.
Advantages
Compiler makes sure that no instance of static class is created. In previous version of C#, the constructor has to be marked private to avoid this from happening.
Also compiler makes sure that no instance members are declared within a static class.
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