Eclipse 错误的解决办法

在Eclipse中导入其他项目，报下面2个错误。将项目所需的jar都引入了。依然还存在这个问题。

1.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

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

解决办法：
1.将JRE先remove掉，然后重新引入JRE即可。(Project->properties->Java Bulid Path )