Note the Java platform for version 1.5.x is called J2SE 5.0 (not Java SE 5). As of version 1.6, the name is simplified to Java SE. So the platform for version 1.6.x would be Java SE 6. Note there is no dot (i.e., it is Java SE 6 not Java SE 6.0). See Java SE Naming and Versions for more.