I think the best way to learn Java is use it in a project,but most of internal Application is under Windows,So we can not find a good project.
I agree with cloud that internal IT tecnology get behind one or two years.
I partly agree with king.If you code the front-end program
and just want to make your homepage more beautiful,you needn't
Java.If you code some portable program or medium component,
Java is one of you best choices.
I think the advantages of java are its language architecture
and the portable character.