why cant static methods use non static variables code example

Example: can non static method access static variable

Yes, a non-static method can access a static
variable or call a static method in Java.
There is no problem with that because of
static members . both static variable and
static methods belongs to a class and can be
called from anywhere, depending upon
their visibility. For example, if a
static variable is private then it can
only be accessed from the class itself,
but you can access a public static variable 
from anywhere by calling with classname.