The folders "Classes","cocos2dx","cocosdenshion" and "extensions" in Android projects are invalid

Sorry,my English is poor,but this problem has confused me for a long time.I try my best to solve it,but I don’t find solutions.So I come here for help.
I find the property “Location” for the folder “Classes” is “COCOS2DX/samples/Cpp/SimpleGame/Classes” ,but the location cannot be resolved.So I cannot find any file in the folder “Classes”.

If you are using Eclipse to run Cocos2d-x. Select your project in Package Explorer right click it. Select Properties~~>Resource~~>Linked resource and add COCOS2DX and select cocos2d-x folder. Clean, build and you should have acces to those folders.

Thank you
Rasputin Wojandos wrote:

If you are using Eclipse to run Cocos2d-x. Select your project in Package Explorer right click it. Select Properties~~>Resource~~>Linked resource and add COCOS2DX and select cocos2d-x folder. Clean, build and you should have acces to those folders.