Class (Static) Variables and Methods
Class variables (not instance variables) and class methods are shared by all instances of the class.
There is only one copy of a class variable.
protected static int numInstances = 0; // a class variable
MyObject() { numInstances++; } // a constructor
public static void main(String [] argv) {} // a class method
Class variables and methods can be used even if there are no instances of the class. Class variables can serve as global variables in a program.