Style 1 - UUID import java.util.UUID; public class GenerateUUID { public static final void main(String... aArgs){ //generate random UUIDs UUID idOne = UUID.randomUUID(); UUID idTwo = UUID.randomUUID(); log("UUID One: " + idOne); log("UUID Two: " + idTwo); } private static void log(Object aObject){ System.out.println( String.valueOf(aObject) ); } } Example run : >java -cp . GenerateUUID UUID One: 067e6162-3b6f-4ae2-a171-2470b63dff00 UUID Two: 54947df8-0e9e-4471-a2f9-9af509fb5889 If Java 5 is not available, then there are other more laborious ways to generate unique ids Style 2 - SecureRandom and MessageDigest import java.security.SecureRandom; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class GenerateId { public static void main (String... arguments) { try { //Initialize SecureRandom //This is a lengthy operation, to be done only upon //initialization of the a...