Enthuware

One of the constructors of each class is called as a result of constructing an object of class C.

class A
{
  public A() {} // A1
  public A(String s) {  this();  System.out.println("A :"+s);  }  // A2
}
class B extends A
{
  public int B(String s) {  System.out.println("B :"+s);  return 0; } // B1
}
class C extends B
{
    private C(){ super(); } // C1
    public C(String s){  this();  System.out.println("C :"+s);  } // C2
    public C(int i){} // C3
}

pushpull wrote:So while constructing an object of class C, it would try to invoke the default constructor of class B, which is absent, so it can't be called, wherefore there will never be a call to the constructor of class A.

Key Rule: The first line in a constructor must be a call to super() or a call to
this().
No exceptions. If you have neither of those calls in your constructor, the compiler
will insert the no-arg call to super(). In other words, if constructor A() has a call
to this(), the compiler knows that constructor A() will not be the one to invoke
super().
The preceding rule means a constructor can never have both a call to super()
and a call to this(). Because each of those calls must be the first statement in a
constructor, you can't legally use both in the same constructor. That also means the
compiler will not put a call to super() in any constructor that has a call to this().