‘Synon or AS/400’ is a bit non-specific – CA2e aka Synon is a ‘program generator’ and produces functions in a target language – typically RPG. Try the CA 2e support forums for detailed information and questions. – AS/400, aka IBM i, aka iSeries, aka i5 is a big subject. Could you provide information about what you need to do?
Do you have 2e and need to integrate Java functions to the 2e model? – or are you integrating 2e functionality to a Java oriented system.
If you just wish to experiment with Java, then you need to step across from ‘traditional’ (AS/400) and start with the contents at somewhere like