In this example I will show you the usage of an in memory java solution that is available as Open Source Project. JIMFS on Github

You could define the OS depended behavior during the time you are creating the builder for the FS.

  Configuration.unix()
  Configuration.osX()
  Configuration.windows()
  Configuration.forCurrentPlatform()

With the builder you could manage the params like maximal size, available roots and much more.

After you created the configuration, the method build() will create the instance of the configuration. With this you are able to create instances of the filesystem:

final FileSystem fs = Jimfs.newFileSystem(configuration)