JFreeChart

JFreeChart is an open-source framework for the programming language Java, which allows the creation of a wide variety of both interactive and non-interactive charts.
JFreeChart, developed by David Gilbert, is available under the terms of the LGPL license.

Features

JFreeChart supports a number of various charts, including combined charts:

X-Y charts. Time axis is possible.
Pie charts
Gantt charts
Bar charts. It also has built-in histogram plotting.
Single valued that can then be placed over map.
Various specific charts.

It is possible to place various markers and annotations on the plot. JFreeChart automatically draws the axis scales and legends. Charts in GUI automatically get the capability to zoom with mouse and change some settings through local menus. The existing charts can be easily updated through the listeners that the library has on its data collections.
JFreeChart works with GNU Classpath, a free software implementation of the standard Java Class Library.

Use in Software Applications

Aperture Photometry Tool
Eastwood Charts an open-source implementation of the Google Chart API, with charts rendered using JFreeChart, developed by David Gilbert. Eastwood Charts is LGPL licensed.
Isabelle
Thoth: Software for Data Visualization and Statistics