Java Abstract Class

Java Abstract Class:

• An abstract class is declared using the keyword abstract.
• It may or may not contain abstract methods.
• An abstract class must be inherited by some other class.
• If the derived class does not provide the implementation of any abstract method present in an abstract class, the derived class must be declared as abstract.
• Objects of an abstract class cannot be created, but reference can be created.
• Through the reference of an abstract class, only methods of the abstract class implemented in the derived class can be called.
• The abstract keyword cannot be applied to static methods or constructors.

abstract class Base
{
   abstract void show();	
}

class first extends Base
{
	void show()
	{
		System.out.println("show of first");
		
	}

}

class second extends Base
{
	void show()
	{
		System.out.println("show of second");
		
	}

}

abstract class third extends Base
{
   
}

public class Abstract_method {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Base b = new first();
		b.show();
		b = new second();
		b.show();

	}

}