How to check a folder size for Mac OSX?

As the folder gets bigger, especially when I develop android source code, a project could easily go over a few gigabytes. In Mac OSX, the folder size showed is not always accurate. It sometimes can cause confusions in real development. 

A single command to update the folder size is:

          sudo du -h [path to folder]

It will not just print the actual size of the folder, but also updates info displayed in the property window.

As always, you are welcome.