For information about system properties, refer to System Properties in the Using System Resources lesson. You can use the Properties class to manage attributes specific to your Java programs. First the application sets up a default Properties object. This object contains the set of properties to use if values are not explicitly set elsewhere. This code snippet uses the load method to read the default values from a file on disk named defaultProperties .
Applications usually save and restore properties to files on the disk.
Next, the application uses a different constructor to create a second Properties object, applicationProps . This object uses defaultProps to provide its default values. Then the code snippet loads a set of properties into applicationProps from a file named appProperties . The properties loaded into appProperties can be set on a per user basis, a per site basis, or whatever is appropriate for the current program. What's important is that the program saves the Properties to a well-known location so that the next invocation of the program can retrieve them.