Why are there not more opensource easy to use charting libraries for Java?. The only successful opensource project in this area seems to be jfreechart, and it doesn't even have any documentation or examples available.
10 Answers
There is charts4j which is a charts and graphs API. It enables developers to programmatically create the charts available in the Google Chart API through a straightforward and intuitive Java API.
Disclaimer: I wrote charts4j. We will be doing another major release in the next few weeks.
There aren't a lot of them because they would be in competition with JFreeChart, and it's awesome. You can get documentation and examples by downloading the developer's guide. There are also tons of free online tutorials if you search for them.
Good question, I was just looking for alternatives to JFreeChart myself the other day. JFreeChart is excellent and very comprehensive, I've used it on several projects. My recent problem was that it meant adding 1.6mb of libraries to a 50kb applet, so I was looking for something smaller.
The JFreeChart FAQ itself lists alternatives. Compared to JFreeChart, most of them are pretty basic, and some pretty ugly. The most promising seem to be the Java Chart Construction Kit and OpenChart2.
I also found EasyCharts, which is a commercial product but seemingly free to use in some circumstances.
In the end, I went back to the tried and trusted JFreeChart and used Proguard to butcher it into a more manageable size.
I suggest that you take another look at JFreeChart. The user guide is only available to buy, but the demo shows what is possible and it's pretty easy to work out how from the API documentation. Basically you start with the ChartFactory static methods and plug the resultant JFreeChart object into a ChartPanel to display it. If you get stuck, I'm sure you'll get some quick answers to your problems on StackOverflow.
There is JChart which is all open source. I'm not sure exactly what you are graphing and how you are graphing it (servlets, swing, etc) so I would say just look at a couple different ones and see which works for you.
http://sourceforge.net/projects/jchart/
I've also used JGraph but I've only used their commercial version. They do offer an open source version however:
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