How to generate unique positive Long using UUID

Question

I have a requirement to generate unique Long ids for my database primary key column.

I thought i can use UUID.randomUUID().getMostSignificantBits()

Answer 1

Take a look at http://commons.apache.org/sandbox/commons-id//index.html It has a LongGenerator that can give you exactly what you need.

In addition if you are using Hibernate then you can ask it to generate IDs for you (it has several algorithms you can choose from), in if not you can just take a look at their implementation for example http://grepcode.com/file/repo1.maven.org/maven2/hibernate/hibernate/2.1.8/net/sf/hibernate/id/TableHiLoGenerator.java#TableHiLoGenerator)