The project cannot be built until build path errors are resolved

错误信息：The PRoject cannot be built until build path errors are resolved 错误原因：曾经引入了一个不需要的jar包，然后删除了。关掉eclipse再次打开时，就报这个错误 解决方法：右键工程，选择build path->configure build path,弹出的窗口里面选择libraries选项卡，删除jar包，然后选择自己电脑上的jar包，右键build path->Add To build path，即可解决问题