Creating all your own code, so as to set a default file directory is unnecessary and lengthy. A much easier and quicker way of doing it is by just right clicking on the File Chooser itself on Design view and right clicking 'customise code'.
Customise Code for File Chooser
This will show you the vital code for that GUI component. From the drop down box next to the top line of code, select 'custom creation'.
This will allow you to customise what fileChooser =
is assigned to. Between the curly brackets JFileChooser()
you can either hard code in the file directory with speech marks like this.
JFileChooser("C:\Users\user\Documents")
or type in a name that for a variable you created earlier. This variable would hold the file directory. I would recommend the latter option, though either will work fine.
Hope this helps.
p.s. sorry about having to use a link for the photo. I don't have enough privilege yet.