Compiling Java 7 to Java 6

Question

I'm aware that the runtime features of Java 7 are not available with Java 6 but since no new byte code has been added the new byte code invokedynamic is only relevant for non-Java languages, I was wondering how hard it would be to convert Java 7 source code (new switch statement, diamond operator) to pure Java 6 (i.e. to be able to start to convert the source to Java 7 without losing Java 6 compatibility).

Any pointers?

Answer 1

As far as I know, there is no solution for this problem at the moment. The best bet would be to extend retrotranslator to deal with Java 1.7 constructs. The diamond operator should be very easy, since it requires no bytecode modification at all.

Your statement "no new byte code has been added" is not correct: There is a new invokedynamic byte code and more importantly there are several cases where the generated bytecode will not be valid for 1.6 JREs, so retrotranslator would have to fix that.