Most people do not work on a project basis, they do fulltime. I would think companies would add the months together and divide by 12. You may want to just list the months as years/months. The math has to add up though, if you started programming in May of 2004 you only have 21 months of experience. You would have an extensive list of skills for your 21 months. Detail everything you have done for your 21 months.
I am using 21 months has an example, but this is how I would do it. :roll:
Just a suggestion since you have gained all these skills in short span of time from various projects, have a summary section or a table in your resume, which list all different Java/J2EE technology and how many months of experience you have.
and so on...... All depends on how good your resume is and how well you do in your interview. Number of years of experience does not always reflect skill/knowledge of an individual. I have interviewed candidates with 6 years of experience and 3 years of experience. At times candidates with 3 years of experience are better than 6 years. All you have to be is a pro-active learner.