Is there a way to tell if a class was compiled for java6?

Question

How can I do to tell if a java class was compiled for use on a java 6 vm?

Is there an easy way?

Answer 1

It's in the class file format specification. The WP article on the subject includes the current set of version number constants.

Answer 2

In unix,

$ javap -classpath <classpath> -verbose foo.Bar \
  | grep -q 'major version: 50' && echo yep || echo nope

thanks @matt b.