Multivision Java J2EE Developer interview questions

First the recruiter called me, told me something about the process, scheduled a phone interview with me, and sent me a guide for the preparation. Then the interviewer called. It was a very easy technical interview that lasted about 15 minutes. The interviewer asked me to introduce some of the projects listed on my resume. Then asked me some technical questions such as how do you test if a string is valid in date format, why to use classes for oop. The interview ended right there. And I received the offer letter the second day. However I declined it because you have to commit 24 months of employment.