Resolution of the IS missing required source folder problem in eclipse

Recently in the development, several times encountered is missing required source folder problem, but some colleagues on the machine did not have the problem, the entire project was deleted, re-removed from the SVN, the problem still exists.
This problem may cause the project to fail to compile and the project that relies on it.

The cause of the problem:
In a native development environment, the Eclipse.project file may have a reference to the missing folder, but the folder is not available in project, resulting in the folder not being found at compile time.

Workaround:
Select project--> Right--->properties--->java build path-->source, remove the missing folder, and recompile is OK.

Reference Links:
Http://forums.pentaho.org/archive/index.php/t-25817.html

Resolution of the IS missing required source folder problem in eclipse