CODEWITHSUNDEEP
androidandroid-permissions
Philipp
Philipp

Reputation: 11814

How to know when WRITE_EXTERNAL_STORAGE is required

I am upgrading my Android app's Target SDK Version to 23 (Android M) which has the new Runtime permissions (https://developer.android.com/training/permissions/requesting.html). My app has declared WRITE_EXTERNAL_STORAGE in its manifest, which must now me requested at runtime. Of course, I'd like to only request it when necessary.

I have an abstraction for different storage types, one implements local storage through normal File I/O (not the Android Content Provider stuff). In this class, I get a file path (like /mnt/sdcard/... or /data/data/...) and before accessing that file (read and write mode), I want to check if I have to call RequestPermissions for WRITE_EXTERNAL_STORAGE.

So the question is: What's the safest and simplest way to determine whether a file can be read and written without that permission (e.g. because it's inside getExternalFilesDir()) or not?

Upvotes: 4

Views: 3065

Answers (1)

arodriguezdonaire
arodriguezdonaire

Reputation: 5562

You can see here that you only have to ask for WRITE_EXTERNAL_STORAGE when your application needs to write to external storage. But:

Starting in API level 19, this permission is not required to read/write files in your application-specific directories returned by getExternalFilesDir(String) and getExternalCacheDir().

First of all I recommend you to avoid requesting permissions using Intents, because it's a best practice and improves a lot the user experience.

If you can't use an Intent to avoid writing with your app, and you know that some day the user will have to write externally, I think the better would be to ask for the permissions the first time the user takes the "write in external storage" path.

As far as I know, in API23 you only have to ask for permissions once, so I think the easyest way would be to ask for the permissions at the first time that the user needs the functionality, I think that then when he'll execute it again, permissions would remain accepted. You can check your granted permissions with the procedure shown here.

Here you can read:

The user is prompted to give permission once, either at run time or at install time (depending on the user's Android version). After that, your app can perform the operation without requiring additional interaction from the user. However, if the user doesn't grant the permission (or revokes it later on), your app becomes unable to perform the operation at all.

Upvotes: 1

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