What is obtained by Environment.getExternalStorageState ().
One of the following
- "unknown" unknown state
- "removed" removed
- "unmounted" Unmounted
- "checking" Disk checking
- "nofs" unformatted or unsupported filesystem
- "mounted" Mounted and readable and writable
- "mounted_ro" is mounted read-only
- "shared" unmounted, USB mass storage, etc.
- "bad_removal" was removed before being unmounted
- "unmountable" cannot be mounted