Thanks guys - well except for Thomas's typical abrasive remarks, this
time because I ommitted the word 'mask', and the diatribe about that
hex, octal and binary being the same...

Anyways, this is how the rough draft turned out, for those who google
on it -    start++; and end--; not working but that should be easy to
fix:

package cafe;

import static java.lang.System.out;
import java.util.StringTokenizer;

public class GetIPs {

   /** Run the client.
    * @param args for main() */
   public static void main(String[] args) {
       try {
           doIPs();
           out.println("doIPs completed!!!");

       } catch (Exception ex) {
           ex.printStackTrace();
       }
   }

   /** Executa a chamada. */
   private static void doIPs() {

       try {
          Integer ip = getIPAsInteger("192.168.200.200");
          Integer mask = getIPAsInteger("255.255.0.0");
          int  start = ip & mask;
          int end   = start | (~mask);

          // Ignore the network number and broadcast address:
          start++;
          end--;
          boolean done = false;
          int addr = start;
          while (!done) {
            getQuadString(addr);
            if (addr == end) done = true;
            addr++;
          }
       } catch (Exception ex) {
           ex.printStackTrace();
       }
   }

   private static Integer getIPAsInteger(String ip) throws Exception {
       if (ip == null) {
          return null;
       }
       int result= 0;
       StringTokenizer st= new StringTokenizer(ip, ".");
       for (int i= 3; i >= 0; i--) {
         result |= Integer.parseInt(st.nextToken()) << (i * 8);
       }
       return new Integer(result);
   }

   private static String getQuadString(long address) {
       StringBuffer sb = new StringBuffer();
       for (int i = 0, shift = 24; i < 4; i++, shift -= 8) {
         long value = (address >> shift) & 0xff;
         sb.append(value);
         if (i != 3)
         {
                 sb.append('.');
         }
       }
       out.println(sb.toString());
       return sb.toString();
   }
}

Robert