Sathyaish wrote On 04/05/07 10:15,:

   (It would be nicer to quote enough context so someone
can know what Question 1 is without scrambling backwards
through the thread thickets ...)

   For those tuning in late, Question 1 asked whether the
call to the superclass constructor had to be the first
statement in a subclass constructor, or whether it could
come later.  As Sathyaish has discovered, it must be first.

   In some cases, you may need to execute a few statements
to generate the arguments you need for the super-constructor.
You cannot do something like

    SubClass(double[] array) {
       double total = 0;
       for (double d : array)
           total += d;
       // pass array average to superclass constructor:
       super(total / array.length);
       ...
    }

... because the call to super is not first.  What you *can*
do, though, is move the interfering statements to a method
of their own:

    SubClass(double[] array) {
       super(meanOfArray(array));
       ...
    }

    private static double meanOfArray(double[] array) {
       ... find and return the mean ...
    }

   If you need to use this trick, make sure that the "helper"
method cannot be overridden in a sub-subclass!  It will run
before the SubClass instance is fully initialized -- even
before the SuperClass instance is initialized -- so you can
get lots of peculiar trouble if it tries to do something with
the incompletely initialized object.  Making it private and/or
static, as above, is a good defense against that error.