It goes further than that...  What he's describing is stylistic in
nature, but the convention is that it's better to specify it as the
respondent described because it clearly shows that the variable "Sides"
is "an array of Side objects".  In addition, by convention, variables
should always begin with lower case letters and class names with upper
case, so that "sides" should be the proper name.

But the actual problem the compiler is reporting (since it doesn't
enforce coding conventions, only language requirements) is that you have
initialization code (as in "Sides[0] = new Side();") outside of any
method, which is not legal.

Two solutions come to mind, since you say you want the array created and
filled when a new Square is created.  One is to do the initialization in
the constructor.  The second would be to create the array with the
initializations, like this:

private Side[] sides =
   new Side[] {new Side(), new Side(), new Side(), new Side()};

This is often not an option for arrays, but a small one like this can
use it.  It might still be better, depending on what else goes on in
your code, to do it in a constructor.

= Steve =