This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
If you want to append to a file, then you should use the FileWriter constructor with the parameter which specifies that. The constructor you chose always overwrites the data in the file, if it already exists.