When you make a method static, it means that the method can be called without an instance of the class. It also means that the method cannot access instance variables unless it is passed a reference to an object.
Sometimes, it makes sense to make a method static, because the method is associated with the class, but not a particular instance of the class. For example, all the parseX methods, such as Integer.parseInt(String s). This converts a String to an int, but does not have anything to do with a particular instance of an Integer object.
If, on the other hand, a method must return some data which is unique to a particular instance of an object, (like most getter and setter methods), then it can't be static.
