[Cdk-devel] Unsupported major.minor version 49.0

[Egon W. <e.w...@sc...>]

Hi all,

this questions has popped up recently more often again:

if you have problems with getting some CDK code going, please make sure the 
below error is not in the stack trace:

java.lang.UnsupportedClassVersionError: 
org/openscience/cdk/interfaces/ChemObject (Unsupported major.minor version 
49.0)

or something similar.

If so, the actual problem is a mismatch in JVM versions. If not mistaken, 49.0 
(major.minor) equals to Java 5.0 (aka 1.5), while 48.0.

So, if you *do* get this error, it means that you are trying to Java5.0 code 
with a JVM 1.4, which does not work.

Now, CDK releases and packages should be released as JVM 1.4 compatible code, 
i.e. should be compiled with javac from a JRE 1.4.

However, I, for one, tend to have 5.0 installed too, so sometimes accidently 
release or commit to CVS some 5.0-compiled code, which will give the above 
Error when running with a 1.4 JVM.

So, don't worry too much about it. Please let us know if it happens, and we'll 
try to fix the release. BTW, consider upgrading to Java 5.0, and plans are in 
the making to stop supporting Java1.4, because the next generation CML 
support requires 5.0.

Hope this helps,

Egon