Inheritance- Basics - Important Topic for Interview

Guys , Hope you are doing well , Today i am again back with some good article , today i will try to write something which i think is one of the favorite topic of all time for an interviewer.

So Inheritance , Most of you knows what is inheritance but the actual in depth knowledge of inheritance is very much required while you are preparing for interview.
In my earlier post I have talked about Tower of Hanoi problem 
You can also see other Sorting program
Bubble Sort 
Selection Sort
Insertion Sort 

• What is Inheritance  ?
• In general - acquiring the properties and character tics of parent by child. 

 

Class A   // parent class

{ void m1();

void m2();

}

Class B extends A   // child class(class B has method m1 & m2 available)

{

void m3();

void m4();

}

ADVANTAGES OF INHERITANCE

-reduce the redundance 

- reduce the length of code;

NOTE - One class only extends one class (not more than one class)

B b = new B();  // we can access 4 method using b object;

A a = new A();   // only access 2 methods;

Interview Question - recommended to create the object of parent or child class ?? 

ans - child - bcz it is possible to access parent method also;

NOTE - root class is the class which is not extending any class.

-- root class of all java classes -> Object class (package java.lang )

TYPE OF INHERITANCE-

• -single level inheritance
• -multiple inheritance
• -multilevel inheritance
• -hirarical inheritance
• -hybrid inheritance

---SINGLE LEVEL INHERITANCE---

when a class is extending only one parent class and the class is not extended by any other class

Ex- 

Class A {

void m1()

}

Class B extends A 

{

void m2()

}

---multilevel inheritance

Ex- 

Class A {

void m1()

}

Class B extends A{

void m2()

}

Class C extends B {

void m3()

}

--heirarical inheritance

Ex 

Class A

{

}

Class B extends A

{

}

Class C extends A

{

}

Class D extends A

{

}

--multiple inheritance

Ex

Class A

{

void money ()

}

Class B 

{

void money ()

}

Class C extends B, A

{

}

 NOTE - now when c is trying to access , then obviously ambiguity occured for c object which method to call(SO IT IS NOT SUPPORTED BY JAVA)(diamond problem )

 --HYBRID INHERITANCE = MULTIPLE + HEIRARICAL  (java is not supporting multiple so java is not supporting hybrid)

In Next Article we will have Inheritance in depth article , If you have any problem in this post , do let me know , I will try to solve your problem , Do Comment in comment section .

Thanks for Reading

-Noeik