Can an abstract class have a constructor?

Question

Can an abstract class have a constructor?

If so, how can it be used and for what purposes?

Answer 1

yes it is. And a constructor of abstract class is called when an instance of a inherited class is created. For example, the following is a valid Java program.

// An abstract class with constructor
abstract class Base {
Base() { System.out.println("Base Constructor Called"); }
abstract void fun();
    }
class Derived extends Base {
Derived() { System.out.println("Derived Constructor Called"); }
void fun() { System.out.println("Derived fun() called"); }
    }

class Main {
public static void main(String args[]) { 
   Derived d = new Derived();
    }

}

This is the output of the above code,

Base Constructor Called Derived Constructor Called

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