Taken From Eclipse "Help"

You can view Javadoc information by:

Opening the Java editor on a Java file.
Placing the mouse pointer over the element whose Javadoc information you want to view (a method name, for example).
Pressing F2 or selecting Edit > Show Tooltip Description from the menu bar.
To view Javadoc in an external browser:

Opening the Java editor on a Java file.
Placing the caret over the element whose Javadoc information you want to view (a method name, for example).
Pressing Shift+F2 or selecting Navigate > Open External Javadoc from the menu bar
Not sure about the dot  "." however if u use da new version u may assign ur shortcut key as u like.