Android 5.0 Lollipop changes the way your SD card works

Google has brought a new set of tools for developers to
leverage the SD card on your phone or tablet with
Android 5.0 Lollipop . Using a new intent, applications
can now have read and write access to directories on
removable storage — even directories they do not own.
Google at its developer conference this summer
announced it would be addressing this issue, and today
things were made more official with an announcement
on the Android-platform Google group.
Here's what you need to know.
Hey all, in KitKat we introduced APIs that let apps read/
write file in app-specific directories on secondary
storage devices, such as SD cards.
We heard loud and clear that developers wanted richer
access beyond these directories, so in Lollipop we
added the new ACTION_OPEN_DOCUMENT_TREE intent.
Apps can launch this intent to pick and return a
directory from any supported DocumentProvider,
including any of the shared storage supported by the
device. Apps can then create, update, and delete files
and directories anywhere under the picked tree without
any additional user interaction. Just like the other
document intents, apps can persist this access across
reboots.
This gives apps broad, powerful access to manage files
while still involving the user in the initial selection
process. Users may choose to give your app access to a
narrow directory like "My Vacation Photos," or they
could pick the top-level of an entire SD card; the choice
is theirs.
OK. If you're not an Android application developer, that
looks pretty complicated. In fact, it is pretty
complicated, so it's a good thing that Google did most
of the work. But we can try and simplify things a bit.
Using this new method, a developer can now declare a
permission on installation (that's part of that list of
items we usually gloss over) to do "things" on device
storage — including removable (read: SD cards) storage.
One of the things they can do is allow you to choose
what folder(s) on the SD card you want the application
to be able to change. This could be one folder — like
"Music" — or the top level folder. Anything inside this
directory can be read, written, and possibly deleted.
Simply put, this means that an app like Poweramp can
now edit tags on the songs you have in the Music
folder. Or a photo editor can save to the Pictures folder,
and not just its own folder. Or a file manager can move
files around on the SD card. All the developer needs to
do is update the app with the new methods.
There will be issues with some apps. We can count on
that. And you'll need to allow for a new permission that
gives an app almost unfettered access to your device
storage — both internal and external. But this is a
(mostly) safe way to allow applications to have access
to the storage on your device that bypasses standard
filesystem commands in favor of a document model.

Via : Android Central