A subclass object would invoke superclass constructor?

[jaspreet atwal]

Hi Guys,
I have a superclass with a constructor superclass().
I have a subclass that extends superclass and has its own constructor.
I create an object of subclass
subclass obj = new subclass();

Now my question is would this also invoke constructor for superclass??

[Kelvin Chenhao Lim]

Yes. The first statement of every class's constructor must either invoke another constructor (e.g. "this(42);") or a superclass constructor (e.g. "super(42);"). If neither is explicitly specified in your constructor code, the compiler will automatically add a call to the no-arguments superclass constructor (i.e. "super();").

[marc weber]

This is easily demonstrated with the following test code...

class SuperClass {
  SuperClass() {
    System.out.println("In SuperClass constructor.");
  }
}
 
class SubClass extends SuperClass {
  SubClass() {
    System.out.println("In SubClass constructor.");
  }
}
 
class Test {
  public static void main(String[] args) {
    System.out.println("Calling SubClass constructor...");
    SubClass sub = new SubClass();
  }
}

Consider: If SubClass extends SuperClass, then any instance of SubClass IS-A SuperClass. So the first step in creating an instance of SubClass is to create an instance of SuperClass.

[jaspreet atwal]

Originally posted by marc weber:
This is easily demonstrated with the following test code...

class SuperClass {
  SuperClass() {
    System.out.println("In SuperClass constructor.");
  }
}
 
class SubClass extends SuperClass {
  SubClass() {
    System.out.println("In SubClass constructor.");
  }
}
 
class Test {
  public static void main(String[] args) {
    System.out.println("Calling SubClass constructor...");
    SubClass sub = new SubClass();
  }
}

Consider: If SubClass extends SuperClass, then any instance of SubClass IS-A SuperClass. So the first step in creating an instance of SubClass is to create an instance of SuperClass.

Marc, This clears my confusion. Thanks!!