This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
Java started with version 1.0, and went on with this numbering until 1.4.2. Then they introduced Java 5.0, 6 and now 7. However, these last three each have two version numbers. Java 5.0 is the same as Java 1.5.0, Java 6 is the same as Java 1.6.0 and Java 7 is the same as Java 1.7.0. 5.0, 6 and 7 are the public version numbers, and 1.5.0, 1.6.0 and 1.7.0 are the internal version numbers.
Please explain your question better. Are you unfamiliar with the Java™ numbering system? Try this Wikipedia page and see whether that helps. If not, tell us more precisely what you want to know. I think that Wikipedia page is slightly imprecise, calling Java5 JavaSE5.