Java developers

Hi. I've been in this community for a while, but have never posted. I'm just learning java this year in school, so basically i'm a newbie.

I'm writing a program (for fun, not for school) that will take my AIM history and use it to make an HTML file that lists statistically who i chat with most, blah blah. (Yea kinda lame, i know) Now every person i talk with has their own directory in my AIM history directory, and i wanted to take the easy way out and just use the length method of the File class on each directory to determine its size. But this of course does not work. I was curious as to if there is any way to determine the size of the contents of a directory (some method that i just am not seeing for whatever reason) without actually going into the directory and finding the size of each item separately and combining them to get the total size (although i imagine this is how any such method would do that anyway).

Okay, thanks!

Two questions.
1) How do you (if it is possible) make a dynamic array? A user is entering data in and I don't know how many entries there will be. Is there a way or am I just stuck guessing?

2) Using a DefaultTableModel the customer inputs one line at a time, the data goes into the array and the row is cleared. And then the customer can either input a new row or hit show all (which will show the data in the array). My problem is that the cell that is still selected the data stays there after the row is cleared (the data goes into the array fine). If I select another cell, that one stays. If I select another cell and then the column header it clears it all.

Thank Ye.