You should be able to evaluate someone's ability to program without ever asking them to write any code, or without them ever having even heard of the language you're going to have them programming in.
I've never met a programming language that I couldn't learn and be competent at in about a week. Everything about programming has nothing to do with particular languages.
The "you need 5 years of java experience" is the kind of requirement that HR robots and hiring managers who aren't programmers look for. They look for someone having already done the job as proof that they can do the job. Yet, someone with 5 years java experience is going to be as good of a C# programmer as they were a Java programmer, even if they've never heard of the language before being hired.
PS- Please don't take this personally, I'm assuming your an engineer, but if you're a designer or marketing guy and are not sure how to hire a programmer, don't take this as derogatory at all. Programming is like driving a car. It is an ability, that is improved with learned skills, but it is not specific to the particular language. IT is like thinking a woman who owns a volkswagon bug can't drive a fiesta because she's got 5 years of "bug experience"