Exception in thread "main" java.lang.AssertionError: x < 0 at AssertDemo.main(AssertDemo.java:6) For either example, running AssertDemo without the -ea (enable assertions) option results in no output.

Why use typesafe enums, not enumerated types. An enumerated type specifies a set of related constants as its values. Examples include the days in a week, the standard north/south/east/west compass ...