What is Abstract Class in Java With Example | Full Stack With Java

Abstract Class In Java With Example | Full Stack With Java Course by Pankaj Sir

Abstract Class in Java :

  1. An Abstract Class Can Consist of Both Complete and incomplete Methods.
  2. An Abstract Class Can Consist of Static and non-Static Members.
  3. An Abstract Class is Zero to 100% incomplete.
  4. An Abstract Class Can Consist of Main Method.
  5. Object of abstract Class can not be Created but Reference Variable of abstract Class Can be Created.

Example 1

public abstract class A {
public void test1() {   // correct
}
public void test2(); // Error
public abstract void test3();  // correct
}

Example 2

public abstract class A {
abstract public void test();
}
public class B extends A {
@Override
public void test(){
System.out.println(20);
}
public static void main ( String[] args ){
B b1 = new B();
b1.test();
}
}
Output : 20

Very Important Point of An Abstract Class

  1. Abstract Class does Not Support Multiple Inheritance.

Example 3

public abstract class A {
}
public abstract class B {
}
public abstract class C extends A,B {  // Error
}

2. interface to Class and interface to abstract class Allowed but class to interface and abstract class to interface not Allowed

Abstract Class in Java With Example
Abstract Class in Java With Example

Example 4

public interface A {
public void test();
}
public abstract class B implements A {
}
public class C extends B {
@Override 
public void test() {
System.out.println(100);
}
public static void main( String[] args ) {
C c1 =  new C();
c1.test();
}
}
Output : 100

Difference Between Abstract Class and Interface

Sr No.Abstract ClassInterface
1Cannot Support Multiple InheritanceSupports Multiple Inheritance
2Can Create Static / Non- Static VariablesAll Variables By Default are Static and Final
3An Abstract Class can be 0 to 100% incompleteInterfaces are 100% incomplete.

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