Error:Execution failed for task ':app:clean'.
> Unable to delete directory: D:\AndroidWorkPlace\HelloJni\app\build\intermediates\classes\debug
Error:Execution failed for task ':app:incrementalDebugJavaCompilationSafeguard'.
> java.io.IOException: Could not delete path 'D:\AndroidWorkPlace\HelloJni\app\build\intermediates\classes\debug'.
这个\app\build\intermediates\classes\debug文件夹里面装的是class文件，所有类和R的class，报错是因为这个debug文件夹为空了
解决方法：退出程序，找到项目地址，打开app 如：D:\AndroidWorkPlace\HelloJni\app
删除build，再用Androidstudio打开会自己重新生成class文件，ok啦
