IDEA 2020报“java：程序包XXXX不存在”或“java：找不到符号”

试了很多，最终这个解决了问题

https://blog.csdn.net/changruhe/article/details/108445144?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-5.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-5.channel_param