Java 1.02: 250 classes. Slow with lots of bugs.
Java 1.1: 500 classes. A little faster. Friendlier, gaining popularity, and a better GUI code.
Java 2.0: 2300 classes. Much faster. Became the language of choice for new enterprise and mobile applications.
Java 5.0: 3500 classes. More powerful (Easier to develop). Changes to the language itself making it more easily understood as well as implemented features that were popular in other languages at the time.
There are more versions -- however my Java booklet was published in 2002.