Eclipse how to link a jar containing javadocs/source with its binary?

Question

I would like to have the javadoc comments contained in a jar file show in eclipse when I hover over a class.

For example, after downloading JODA-2.0, three jars are

Answer 1

1. Right click over the project -> Build path -> Configure build path
2. In the new window, go to the "Libraries" tab.
3. Select the library and expand it.
4. There are 4 child options. Select "Javadoc location" and click the "Edit" button on the right.
5. Now you can add a jar file containing the docs. This would be just a zip file with the extension changed to jar. Make sure inside the jar the index.html is in the root. You can press the "Validate" button to check everything is ok.