I typed in the first example program from Java in a Nutshell and
installed the Java SDK from Sun's website on my WinXP system.  The
code complies cleanly, but when I run it I get:

C:\home\java> java Factorial.class 4
Exception in thread "main" java.lang.NoClassDefFoundError:
Factorial/class

It looks to me like the code clearly defines the class.  Do I need to
put the files in a particular location?  I've got the .java and .class
file in my current working directory.

Factorial.java:

public class Factorial {
 public static void main(String[] args) {
   int input = Integer.parseInt(args[0]);
   double result = factorial(input);
   System.out.println(result);
 }

 public static double factorial(int x) {
   if (x < 0)
     return 0.0;
   double fact = 0.0;
   while (x > 1) {
     fact = fact * x;
     x = x - 1;
   }
   return fact;
 }
}

Here's the Java version info:
java version "1.4.2_03"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_03-b02)
Java HotSpot(TM) Client VM (build 1.4.2_03-b02, mixed mode)

Richard Anderson