Here are various options:
- java.util.Properties
- java.util.prefs.Preferences (since Java 5)
- Commons Configuration
- jConfig
- JFig
- Carbon's Configuration Service
You might want to read Comparison of Commons Configuration With JFig and JConfig and Configuring your Applications using JFig for some feedback from various users.
Personally, I've used jConfig and it was a good experience.
