How to close the gap

I am a senior developer (currently with emphasis on Java). Unfortunately the division I work in doesn’t emphasise work with Java technology and I get the feeling that a major technical gap is being generated. Let me explain: as I’ve been looking at other jobs, I’m now being told that my experience of Java Technology is not up to date (eg. older Java version etc.). What would be the quickest possible way to familiarise myself with the latest technical skills in demand regarding Java?