Hi as per android documentation the drawable folder needs to have multiple sub-directories for images of different dpis. However in Android Studio creating any sub directory
You don't create subfolders of the drawable folder but rather 'sibling' folders next to it under the /res folder for the different screen densities or screen sizes.
The /drawable folder (without any dimension) is mostly used for drawables that don't relate to any screen sizes like selectors.
See this screenshot (use the name drawable-hdpi instead of mipmap-hdpi):

The standard procedures are:
Simply go to project Explorer and change your View from Android to project from drop Down and you are good to go.There you can simply create folder like we do in Eclipse. And in android project view it is hidden but when you switch to project. You can create folder like drawable-hdpi,drawable-xhdpi.
You need to access image IDs using R.mipmap.yourImageName