Javav

A utility to print the target version of Java class files.

Installs a javav executable to print the target version of one or more Java class files.

For example:

> javav ThisClass.class ThatClass.class
1.6 (50.0 0x32) ThisClass.class
1.5 (49.0 0x31) ThatClass.class

Java VM Specification 4.1 The ClassFile Structure

http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html#74353