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.

  • 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

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