Question

My program

class Building {
Building() {
    System.out.print("b ");
}

Building(String name) {
    this();
    System.out.print("bn " + name);
}
};

public class House extends Building {
House() {
    System.out.print("h "); // this is line# 1
}

House(String name) {
    this(); // This is line#2
    System.out.print("hn " + name);
}

public static void main(String[] args) {
    new House("x ");
}
}

We know that compiler will write a call to super() as the first line in the child class’s constructor. Therefore should not the output be:

b (call from compiler written call to super(), before line#2

b (again from compiler written call to super(),before line#1 )

h hn x

But the output is

b h hn x

Why is that?

Answer 1

When a constructor starts with a call to another constructor (either this or super), the compiler does not insert a call to the superclass’s default constructor. Thus, the calls tree is:

main
 \-> House(String)                (explicit call)
      |-> House()                 (explicit call)
      |    |-> Building()         (implicit call)
      |    |    |-> Object()      (implicit call)
      |    |    \-> print "b "
      |    \-> print "h "
      \-> print "hn x"