Possible duplicate:search files in eclipse
How to search for a specific word in the entire workspace in Eclipse?
select a workspace and press Ctrl + H
In the menu "Search" there is an option "File", which brings up a dialog. Fill in the word you are looking for and a template to limit your search for files.
Entering "Search" in the help system would give you this.
Select the workspace in the package explorer, open the file search dialog box, enter a specific world and * as a file template, limit the search to the selected one.
*