CODEWITHSUNDEEP
androidsharedpreferences
Desmond.Tan
Desmond.Tan

Reputation: 53

Android: Cannot access other app's SharedPreference

I've been searching for days to solve this, but with no success.

I want to get the shared preference settings from my old app and put it on to my new app. but I've encounter some security issue (suspect).

my code:

Context c = createPackageContext("my.app.pkg", Context.CONTEXT_IGNORE_SECURITY);            
SharedPreferences sp = c.getSharedPreferences("my.app.pkg", Context.CONTEXT_IGNORE_SECURITY);

Running the code above giving me this:

Attempt to read preferences file /data/data/my.app.pkg/shared_prefs/my.app.pkg_preferences.xml without permission

even thought the object sp is not null, but it does not retrieve anything from my old app.

I tried googling around and seems like most people can run the code above with no errors. Is there anything I've missed out?

Upvotes: 5

Views: 5991

Answers (3)

sciutand
sciutand

Reputation: 3279

You can indeed share preferences across applications. That's why it's called SharedPreferences.

What you need to do is make sure both application are signed with the same certificate and they both share the same SharedUserId in the AndroidManifest.xml file: read here.

This is because the SharedPreferences you get from

PreferenceManager.getDefaultSharedPreferences(context)

has always MODE_PRIVATE.

However in an application you can also get a SharedPreferences object within a Context with the following:

SharedPreferences prefs = getSharedPreferences("my_public_shared_prefs", MODE_WORLD_READABLE);

which you can freely retreive from another app with the following:

Context context = createPackageContext("my_target_app_package", Context.CONTEXT_IGNORE_SECURITY);            
SharedPreferences prefs = context.getSharedPreferences("my_public_shared_prefs", MODE_WORLD_READABLE);

Make sure you don't store any private information there because it's WORLD readable, which means you and anyone else can read that data.

To finish, if you want to retrieve the SharedPreferences of your old app you will need to update the old application with a SharedUserId in the Manifest file.

Upvotes: 1

mxk
mxk

Reputation: 43534

We've done exactly this for our Android book Android in Practice. The key is to use the same process and user ID for both apps. The sample code and sample apps are on Google Code (SharedProcessApp1 and SharedProcessApp2). You can go from there.

Upvotes: 4

jeet
jeet

Reputation: 29199

Android APplications runs in their own sandbox, so one application can not access data of other activity. BUt If an application want to share some of its data, this can be achieved by ContentProvider.

See Content Provider: http://developer.android.com/guide/topics/providers/content-providers.html

Upvotes: -1

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