To view the Javadoc
for a class in an Eclipse window, place the text insertion point on
a class name in the source code and press F1. A Help view appears
in the workbench. The first link in the Help view is a link to the
Javadoc, if Javadoc is available for the class.
The link in the Help
view is context sensitive, and changes if you reposition the insertion
point to a different class.