Inheritance in Java - creating an object of the subclass invokes also the constructor of the superclass. Why exactly

public class A {
     public A() {
         System.out.println("Hi!");
     }
}


public class B extends A {
     public B() {
         System.out.println("Bye!");
     }

     public static void main(String[] args) {
         B b = new B();
     }
}

public class B extends A {
    public B() {
        super();
        System.out.println("Bye!");
        }
    ...
    }

class Q {
  int i;
  public Q() {
    // set default value
    i= 99;
  }
}

class Z extends Q {
  public Z() {
  }
}

public class A {
     public A() {
        x = 1;
     }
     private int x;
     public int getX() {
        return x;
     }
}


public class B extends A {
     public B() {
     }

     public static void main(String[] args) {
         B b = new B();
         System.out.println(b.getX()); // should print 1
     }
}