Hi, Do you know any nice freeware that will take my java sources and will generate class diagrams from them?
It's called UML. Knowing that keyword, you should have more success in Google. If you're using an IDE like Eclipse, you can also look for a plugin here or here. Good luck.
Netbeans has a UML plugin that can reverse engineer class diagrams from Java source.
If you use maven, one nice way of generating UML from your classes is by generating JavaDocs and adding the UMLGraph doclet. See the following link:
http://maven.apache.org/plugins/maven-javadoc-plugin/examples/alternate-doclet.html
The nice thing about this is that it becomes simple to integrate into a nightly build.
AmaterasUML is a free eclipse plugin that works pretty well. You can drag and drop classes from the package explorer to the diagram, and export to png.
ArgoUML is the best free UML tool. MagicDraw is the best commercial UML tool. And IDEs have plugins to create UML diagrams too (Eclipse and Netbeans to name two).
Try Hierarchy. (It does not auto-generate UML, but the source is available ...)
See http://www.reversejava.com for a dynamic reverse engineering application which generates UML Sequence diagram and view of Participating Class diagram from any Java Application at runtime All you have to do is just run your application and sit back. Reverse Java runs in background tracing all the activities happening inside your application and creates UML diagram for you.
You also have options for, excluding packages,editing the Sequence diagram and exporting the diagrams as PDF or Image.
And its not expensive !
I use the ObjectAID UML plugin for eclipse. It's a very nice free tool that lets you build UML diagrams that you can navigate.
See also this question for more Eclipse plugins that allow you to do this with UML.