Save android studio project

One of the ways to save the app is to make a backup of the "src" folder of the project, there will be all your code classes, activity's, strings, manifest, etc. to restore the project create a blank project and replace the folder "src". I usually create a .zip and save to Google Drive or Dropbox, another way is to create a repository in github or bitbucket is usually more used, I also use it, having the possibilities of public or private repositories (this is paid in github) and versioning of your files.