Questions to ask in an interview

I've worked with a lot of people in my time.
I've worked with lots of really smart people, and lots of really, really dumb, lazy, unqualified people.

I prefer the former. It's become so very clear to me how important it is to keep bad people out. I'm better off having an un-filled position that have it filled with the wrong person. (It's probably the same with romantic relationships - but I digress).

OK - so there are lots of Java interview questions all over the iternets, but here are some questions I like to ask when interviewing a candidate for a Java developer position (and sometimes beyond)

1. Have you read Effective Java? This is a good litmus test. This is a fundamental book - and if you haven't bothered to read it I probably don't want you on my team. It's not an absolute rule - but it's a decent starting point. 
2. What books have you read? Aside from Effective Java I like to hear Java Patterns - then maybe some technology -specific books on whatever technology's listed in your resume, especially from your last job. Maybe it's Springs or Hibernates or XMLs or PHPs or whatever. Point is, there's only so much you can get out of a quick intro read on a website and form your own exposure - if you really want to know it  then learn from an expert.
3. What did you read most recently or what are you reading now? What I am trying to find out here is, what's the candidate's approach and attitude towards continuous learning? The very last thing I want is someone who learned to write Java code in a class in college a few years back, or read the intro on the Oracle site. It's a continuously evolving field - if ever there was a field which requires a lifelong learning, this is it. My most recent read is Java concurrency in practice - which I highly recommend.
4. Why do you want to work here? This always seemed to me like a really stupid and annoying question when people ask me that at interviews. It's as legitimate as an interviewee asking 'Why do you want to hire me'. As an applicant I think (to myself) 'I didn't say I wanted to work here - it's an interview. It's a two-way evaluation'. Maybe a better question is, 'What motivates you to come to work'? The truth is there are multiple reasons why somebody would want to come to work, and they are all important. Yes, I want to be paid for my work - if everything else was perfect about a job but it had no pay, I'd definitely have to pass. I want to work with smart, motivated people that I like. I would prefer being the least knowledgeable and dumbest person in the room - but the reality is I typically find myself coaching others. I like to be challenged with new ideas, technologies and tools. 
5. How do you manage your email inbox? This is also a no-single-right-answer type question, but it gives me a good idea of your organizational skills. That's probably a good topic for another post.
6. I am always curious about the candidate's outside-of-work work - like open source projects, StackOverflow posts, SIG memberships etc - but that's not at all a requirement. I understand perfectly well that people have a life outside of work - homes, families, hobbies, twins to feed and change and put to bed, dinner to cook and clean up from - so if I get into bed and manage to watch a half hour YouTube on building JIRA workflows, it's sometimes still a good night. 

It occurs to me there are also questions I like to ask of an interviewer when I'm sitting on the other side of the table... 

1. Describe your development process. This is also a good litmus test question. If I don't hear something about 'code reviews' - well then there's a really good chance people at the helm don't know what they are doing. It's such a fundamental part of a good software development process that if it's not there - well that means I'm probably walking into a mess of someone else's crappy old code. 
2. Describe your testing methodology. This is also a sort of a litmus test - but it's not a yes or no situation, there is more of a spectrum here. Automated unit tests like jUnit are a great way to start - I don't want to hear that 'developers test their own code'. If there's a UI testing framework set up then so much the better. I ask about what kind of load testing and performance testing you do (if at all). 
3. More open ended questions - say, what do you do to help your employees succeed? It's a flip side of the 'why do you want to work here' question. 

I'll probably think of others...