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💡Definition-

Abstraction is a concept of showing only functionality and hiding procedure.

In java, only name of method is given and not the body.

-Abstraction can be applied on classes and methods using abstract keyword.

– In abstraction we focus on “what” the object does instead of “how”.

Quick comparison between abstract classes and abstract methods:-

Feature	Abstract Class	Abstract Method
Definition	A class that cannot be instantiated and serves as a base for one or more derived classes. It may contain both abstract and concrete methods.	A method that has no implementation and must be implemented by a derived class.
Use	To provide a common interface and implementation for related classes.	To define a common interface for derived classes to implement.
Syntax	abstract class ClassName { ... }	abstract void MethodName();
Can be declared in	Class	Class or interface
Can have concrete methods	Yes	No
Must be implemented in derived class	No	Yes

💡1- abstract class

– Only abstract class can have abstract methods

-Abstract class can have normal methods too.
-Object of abstract class can’t be created directly
– abstract classes should be inherited to be useful

[Think of an abstract class as an almost complete car by your dad who left over the choice of engine to be provided by you.]

💡2- abstract method

– abstract method can’t have method body
– abstract methods should be overridden to be useful.

code samples are here

1- Abstraction

package abstraction14;

abstract class A{

abstract void shw();
abstract void disp();
}

public class ExampleAbstraction extends A {

@Override
void shw() {
System.out.println("hi");
}

@Override
void disp() {
System.out.println("bye");
}
public static void main(String[] args) {

ExampleAbstraction e1=new ExampleAbstraction();
e1.shw();
e1.disp();
}
}

Interview Questions —

• what is abstraction in real world?
• How to create object of abstract class?