I wrote the other day about how the java 2 collections has been done away with in favour of vector and hashmap etc in J2ME.
Unfortunately the Vector class you find in J2ME is not the same as what you get in J2SE, it's incomphrehensible why they might have wanted to change that.
Despite these issues J2ME really is a wonderfull technology. The support for audio and video in J2ME is just amazing. The flip side of course is that there is no guarantee that all smart phones will support this api but stil ...