This is a supplement answer related to the OP:
An easy and reliable solution to add Javadocs comments in Eclipse:
To use this tool, right-click on class and click on JAutodoc.
To quickly add a Javadoc use following shortcut:
Windows: alt + shift + J
Mac: ? + Alt + J
Depending on selected context, a Javadoc will be printed. To create Javadoc written by OP, select corresponding method and hit the shotcut keys.
Project > Generate Javadoc....
In the Javadoc command: field, browse to find javadoc.exe (usually at [path_to_jdk_directory]\bin\javadoc.exe).
Check the box next to the project/package/file for which you are creating the Javadoc.
In the Destination: field, browse to find the desired destination (for example, the root directory of the current project).
Click Finish.
You should now be able to find the newly generated Javadoc in the destination folder. Open index.html.
You can also do it from command line much easily.
From command line run:
javadoc YourClassName.java
To batch generate docs for multiple Class:
javadoc *.java
Source: Stackoverflow.com