I think you are implementing JComboBox in a perverted way,
JComboBox is for sending information to a DataBase, array, ect; but
hey that is my humble opinion. Coders always impress me with their
canny implementations. And I believe yours will work by using:

YOUR_JCOMBOBOX_OBJECT_NAME.setEditable(true);

---> look up JComboBox in your API, if you do not have that
downloaded from Sun, get it, i use it everyday...
goodluck...