R文件没自动生成的解决办法（R cannot be resolved to a variable)

http://www.2cto.com/kf/201207/142915.html

http://blog.youkuaiyun.com/jason0539/article/details/9708025

http://blog.sina.com.cn/s/blog_76c545390101fip1.html

http://blog.youkuaiyun.com/chishui2/article/details/8777973