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

错误提示:The project was not builtsince its build path is incomplete. Cannot find the class file forjava.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

 

今天启动程序出现如上问题，昨天还好好的，只好网上google一下，说问题可能是系统中有jre多个，Eclipse在建立项目时，会自动参照你的jre路径，但多个版本就没办法加载了。
解决办法：
在eclipse中把不同到的jre删除，这样就行了。