Sams Teach Yourself Java™ in 24 Hours, Sixth Edition

Reading and Writing Configuration Properties

Java programs are more versatile when they can be configured using command-line arguments, as you have demonstrated in several applications created in preceding hours. The java.util package includes a class, Properties, that enables configuration settings to be loaded from another source: a text file.

The file can be read like other file sources in Java:

• Create a File object that represents the file.

• Create a FileInputStream object from that File object.

• Call load() to retrieve the properties from that input stream.

A properties file has a set of property names followed by an equal sign (=) and their values. Here’s an example:

username=leptonlastCommand=open databasewindowSize=32

Each property ...