No casting is performing to find super class for the class that you are trying to cast. For example you can cast a double into an integer since an integer is a double. But no you need to save it to another variable since the old one probably is declared with different type.
double myDouble = 2.0;
int myInt = (int) (myDouble);
that is going to give you an integer version of myDouble but myDouble is still unaltered.