I'm always interested in and looking for new programming jobs.

I've been in my current role for 18 months and I actually quite like it but the language used and the software in general is fairly old fashioned and clunky. I came in and managed to boost the performance of the client-server connection 3-fold after 6 months of using the language. (It's a 10 year old system). The language is a 4GL procedural language with no real bell and whistles.

I've been pushing as hard as possible to get some iPhone stuff going and in my spare time I've written a couple of apps. I had a working proof-of-concept app for one of the MDs written and presentable within a 2 week time frame.

My first language is Java and I love it and would love to get into a Java role but I don't have any experience of programming in it.

What kind of experience is required to get into a Java role (or any more advanced role)? Do I need a portfolio of apps in the given language? Do I need to have years of experience working with the language? Or is it sufficient to have a working knowledge of the language and be able to show that you have a good knowledge of programming principles and a CV showing good skills (i.e. from never seeing my current language to single handedly tripling the performance of the client-server in 6 months).

Would love to get into a role that required a more technical understanding of programming.

I'd suggest making projects to show areas of skill such as algorithms, client/server programming.

Best to have a portfolio they can look at (ideally with source code) so they can see if you are a developer and not just someone that hacks together code, especially if it's technical work in the area you want to learn more about (machine learning or whatever)

I found having stuff on my site people can download and use is good, especially when I can give download figures quickly and easily as well as usage stats from the API, mostly just side project stuff but IMO it's good to see actual code.

If I was hiring I'd want a developer to have knowledge of testing and to know how to do it, it's rarely a learned skill except when needed in the field