Android library project cleaning and rebuilding has problems

Question

Environment:

IDE: Eclipse IDE for Java Developers 3.7.1
Plugin: ADT 14.0.0.v2011101719
Host: Fedora 13 
JDK: 1.6.0_21

Eclipse seems to have problems cleaning and rebuilding projects, when at least one project is an Android Library project, and another is an Android project dependent on the library project.

I building this Application CSipSimple .I getting Some four errors saying as follows :

The container 'Library Projects' references non existing library
'/bin/com_actionbarsherlock.jar'

The project cannot be built until build path errors are resolved

The project was not built since its build path is incomplete. 
Cannot find the class file for java.lang.Object. Fix the build
path then try building this project

The type java.lang.Object cannot be resolved. It is indirectly 
referenced from required .class files

Can anyone known this issue ? if it can be solve any way ?

Answer 1

ok , try these steps,

Go to Project Menu, select Properties. A dialog Box will be appear, In that dialog box, from left side, choose the Android Option , now in the right side choose the Android version you are developing for.

Now again Clean & Build the Project.