Just to add little more :-
Within Constructors:-
Within constructors , this() or super() should be the first statement, since both cannot be first , therefore only one could reside within a single constructor, but somewhere ,within the same class, there is a constructor which has super() as the first statement. ( either it is added by you or by compiler ). When you add , then super can take many forms i.e. super(), or super(with arguments).
Within Methods :-
Within Methods , super() and this() does not work, but but but ....... super.variable_name , this.variable_name, super.method_name(), this.method_name() does work .
Moreover withing methods , there is no restriction for super and this to be the first statement, and moreover there could be this and more both residing within the same method anywhere and may be more than one time.
Thanks
Sahil Rally