学习java基础中，eclipse软件导入别人的项目工程时报错怎么解决？？求大神支招哇
err1:The project was not built since its build path is incomplete. Cannot find the class file for java.lang.CharSequence.
err2:The type java.lang.CharSequence cannot be resolved. It is indirectly referenced from required .class files       

配置错误，路径不对，找不到类文件，