A friend of mine was asking me how to generate a unique ID for his application... As you probably already know Java SE 5 has introduced the java.util.UUID class to easily generate Universally Unique Identifier (UUID). As usual Wikipedia is a great starting point to learn more about UUID.
Generating the unique ID is as simple as calling the method
UUID.randomUUID() in the class. This will give a new instance of UUID that you can now manipulate; for example do a toString() to get the UUID string representation as describe in the specifications; for example