Eclipse change project files location

Much more simple: Right click -> Refactor -> Move.

This link shows how to edit the eclipse workspace metadata to update the project's location manually, useful if the location has already changed or you have a lot of projects to move and don't want to do several clicks and waits for each one: https://web.archive.org/web/20160421171614/http://www.joeflash.ca/blog/2008/11/moving-a-fb-workspace-update.html

You can copy your .classpath and .project files to the root of the new project directory and then choose 'Import...' from the file menu, and select 'General/Existing Projects into Workspace.' In the resulting dialog, locate the root of the new project directory and finish. Make sure that you have deleted the old project from the work space before importing.

There is now a plugin (since end of 2012) that can take care of this: gensth/ProjectLocationUpdater on GitHub.