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Q) What is “Inheritance”?




A)
->inheritance is the mechanism of new entities acquiring from the exiting entities (it is general statement)
->the mechanism of creating new classes from the existing classes with a “is-a” relationship is known as inheritance.
->newly created class is known as “sub class” or child class”.
Child class     - general term
Sub class        - in java
Derived class - in c++
->already existing class is in known as “super class” or “parent class”
Parent class    - in general
Super class     - in java
Base class       - in c++

->”extends” keyword is used to implement inheritance in java.

Ex:

Class A
{
}//super class

Class B extends A
{
}//sub class

->in the above example A is super class and B is sub class.
Is – a relation done by extends keyword. Here “B to A” contains “is-a” relationship but “A to B” there is no relationship.

 

Here A is super class and B is sub class
And “is-a” relation – this is “getting from” relation, not “getting to

->sub classes acquired properties and behaviour from super classes. I.e. a sub class inherits instance variable and instance methods of the super class.
->constructors are not inherited. Because they are not behaviour of the object. They are specialized methods. So the behaviour of the object only inherited.

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