I'm working on an application that requires I save a field between application uses, so that I can retrieve the data during the next use (ex. save username when logged in, retrieve it and pre-populate username field when application is next launched). I've looked around and found a couple ways to accomplish this goal, such as encryption & saving in a file on the local machine, and saving the value in the Windows registry. Are any of these methods better than others for accomplishing this goal? Any other suggestions?
You can store it using the Java Preferences API which will store a small amount of data in a system-specific way. On Windows, I believe it stores it in the registry, but on a Mac or on Linux it will be stored in a manner appropriate to those systems.
The data is stored, for the current user, under a key that is specific to the package of your class plus a string of your choosing. See the Preferences API Overview for more details.