Running a jar from shell script
As already mentioned - you're trying to use byte code compiled by the later compiler with old jvm.
Please note that if your PATH contains multiple java executables of different versions you can switch between them easily using '-version' key.
Suppose you have java5 and java6 at your PATH and java5 is located before java6 there. You can see that java5 is used by default then (if you execute 'java -version' it prints corresponding information). However, you can start java6 easily using command like 'java -version:1.6 ...' (e.g. if you execute 'java -version:1.6 -version' you see that java6 is used).