I have written a couple of Java classes on Max/MSP 5.1.8 on an iMac running Mac OS 10.6.7, as well as recompiling Userpath. They all work fine on my machine. However, when they are run on Macs using 10.5 or 10.4, we get error messages in the Max window as below:
java.lang.UnsupportedClassVersionError: Bad version number in .class file
at java.lang.ClassLoader.defineClass1(Native Method)
Could not load class 'Userpath'
The 'bad version number' message seemed to suggest some kind of version issue with the JVMs, but I updated Java on one of the machines affected and the problem persisted.
I see that the MXJ compiler interface is calling the compiler in the 1.6.0.jdk (which is the only one installed on my Mac). I am not, however, using any Java 1.6 features (I'm probably not using anything that wasn't already available one Java 1.0).
What incantation do I need to make sure that my .class files will run with older JVMs?