请问大佬这个问题该如何解决

/home/nick/study/wildfire/android-chat/imagepicker/src/main/java/com/lqr/imagepicker/adapter/ImageFolderAdapter.java

Error:(15, 27) java: cannot find symbol  symbol:   class R  location: package com.lqr.imagepicker

Error:(73, 56) java: package R does not exist

Error:(107, 52) java: package R does not exist

Error:(110, 58) java: package R does not exist