Frequently Asked Object Oriented Programming OOP Interview questions and answers pdf for freshers and experienced
1. What is Abstract method?
Ans:
Abstract method doesn't provide
the implementation & forces the derived class to override the method.
2. What is Virtual method?
Ans:
Virtual Method has implementation
& provide the derived class with the option to override it.
3. What is Polymorphisms?
Ans:
Polymorphism means one interface
and many forms. Polymorphism is a characteristics of being able to assign a
different meaning or usage to something in different contexts specifically to
allow an entity such as a variable, a function or an object to have more than
one form.
There are two types of
Polymorphism.
Compile time: function or
operator overloading
Runtime: Inheritence &
virtual functions
4. What is Abstract Class?
Ans:
Abstract class is a class that
can not be instantiated, it exists extensively for inheritance and it must be
inherited. There are scenarios in which it is useful to define classes that is
not intended to instantiate; because such classes normally are used as
base-classes in inheritance hierarchies, we call such classes abstract
classes.
Abstract classes cannot be used
to instantiate objects; because abstract classes are incomplete, it may contain
only definition of the properties or methods and derived classes that inherit
this implements it's properties or methods.
Static, Value Types & interface doesn't support abstract modifiers.
Static members cannot be abstract. Classes with abstract member must also be
abstract.
5. When to use Interface over abstract class?
Ans:
Abstract Classes: Classes which
cannot be instantiated. This means one cannot make a object of this class or in
other way cannot create object by saying ClassAbs abs = new ClassAbs(); where
ClassAbs is abstract class. Abstract classes contains have one or more abstarct
methods, ie method body only no implementation.
Interfaces: These are same as
abstract classes only difference is we can only define method definition and no
implementation. When to use wot depends on various reasons. One being design
choice. One reason for using abstarct classes is we can code common
functionality and force our developer to use it. I can have a complete class
but I can still mark the class as abstract.
Developing by interface helps in object based communication. Next>
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