右击有红色叹号的java project Build path>>Configure Build Path
Resource >> java build path Libaries 点击如下图所示的JRE System ....点击右边的remove
删除后，再点击add library
点击jre system library >>next
finish>>ok
右击有红色叹号的java project Build path>>Configure Build Path
Resource >> java build path Libaries 点击如下图所示的JRE System ....点击右边的remove
删除后，再点击add library
点击jre system library >>next
finish>>ok