What is a DEFS file? Configuration file created for BlueJ, a Java development environment; contains administrator settings for the BlueJ program such as the desired language and location of libraries.

More Information There are two ways to change BlueJ configuration settings: To change user options, with the application open, select BlueJ from the menu bar, then Preferences... . You can alter settings in this dialog box. To change administrator options, open the file located at: BLUEJ_HOME/​lib/​bluej.defs . If on a Mac, right-click the BlueJ application, select Show Package Contents , then Contents , then Resources , then Java . You should then see the bluej.defs file and other DEFS files. Once you open a DEFS file, it will contain a list of properties in the following format: property-name = value The property name should never be changed but the values can be changed to alter the configuration.