Version 1.3 of JPlot integrates a number of improvements which allows you to use JPlot without it's GUI. Moreover, you can use JPlot without data files. The JPStream archive contains a simple but fully operational example illustrating of how to create a JPlot graph without its GUI.
To install this archive, decompress, type make, followed by make run. Note: you need JPlot version 1.3 to be installed besides JPStream.
After a relatively long period of rest at the JPlot front, the stable release of JPlot 1.3 has been released. This version includes many minor bug-fixes and includes full support for data streaming. Check out the jpstream package which includes several examples of how to use JPlot as a library. This version was tested with J2SDK 1.4.2.