Where Are Shared Preferences Stored

Where are shared preferences stored?

SharedPreferences are stored in an xml file in the app data folder, i.e.

/data/data/YOUR_PACKAGE_NAME/shared_prefs/YOUR_PREFS_NAME.xml

or the default preferences at:

/data/data/YOUR_PACKAGE_NAME/shared_prefs/YOUR_PACKAGE_NAME_preferences.xml

SharedPreferences added during runtime are not stored in the Eclipse project.

Note: Accessing /data/data/<package_name> requires superuser privileges

what is the difference between shared preferences and internal storage in Android? Where does the data stored?

SharedPreferences stores data in key-value pairs. It stores them mainly in RAM but it also saves a copy to the internal storage. Android provides RAM for storing your code, all the graphics and any temporary data, and it's limited. If you store a lot of key-value pairs (and maybe the values are long Strings), you may indeed use all the RAM for your app and end up with an OutOfMemoryException. That's an indication that SharedPreference is probably not the right method for the data you're trying to store.

The internal storage, instead, is entirely based on Flash memory. Apps have less constraints there, and they can store large amounts of data like images. The internal storage is kinda like a directory, so you create files, read/write on them, delete them etc., so it's different than key-value pairs.

Are shared preferences stored in memory during runtime?

Are shared preferences in Android always read at startup and stored in memory during runtime

Simply Yes till user doesn't clear it manually from setting.

are there more efficient ways to read preferences than this

As JonasCz said in comments.. this is the most common and developer friendly way till now.

How to create, read and write a sharedPreferences file?

You can create SharedPreferences in you project without finding it in the project directory. This is actually stored in your project folder in the app file system once created (/data/data/YOUR_PACKAGE_NAME/shared_prefs/YOUR_PREFS_NAME.xml).
But for creating, updating and retrieving you do not want to go there.

To Create SharedPreference

SharedPreferences.Editor editor = getSharedPreferences("MyPreference", MODE_PRIVATE).edit();
 editor.putString("name", "Nathan");
 editor.putInt("id", 1000);
 editor.apply();

To retrieve

SharedPreferences prefs = getSharedPreferences("MyPreference", MODE_PRIVATE); 
String name = prefs.getString("name", "Blank Name"); //"Blank Name" the default value.
int idName = prefs.getInt("id", 0); // 0 is the default value.

Please go through the below link for more details.
https://developer.android.com/reference/android/content/SharedPreferences?hl=en

Flutter SharedPreferences Windows location

According to the Shared Preferences documentation, it's stored in the local AppData folder for Windows.

From a scan of the code for the Windows platform interface, this seems to be the path obtained by pathProvider.getApplicationSupportPath(). You could call this in your code to get the specific path of where the file is stored.

Android SharedPreferences or SQLite Storing

Shared Preferences:

All shared prefs are stored in /data/data/[package name]/shared_prefs/[app name].xml, so i think there's no limit based on aechitecture.

Shared Preferences is nothing but a simple table which has two columns. (key, value).

Shared Preference size 8192 characters according to this documentation:
http://developer.android.com/reference/java/util/prefs/Preferences.html#MAX_VALUE_LENGTH

advantages:

• Fast retrieval
• Easy to understand and program

disadvantages

• Maintaining Keys are difficult if we store a lot of values.
• User can clear this at any time.

Database:

When we have a lot of values to store with complex structure, we are left with only one great solution, ie. DB.

advantages

• We can maintain structure of data.
• Android has nice and simple APIs to handle sqlite operations.

disadvantages

Operation is little bit slow comparing to shared preferences.
user can clear this at any time.

Reference

Dealing with shared preferences stored in a library

I assume you are asking whether your library can share prefs with the top level app, not whether the free version can share with the full version.

The api docs mention that you can't share prefs outside of a given process, so is it possible that since you (probably) have two different packages (one for lib, one for top-level), the prefs you get in the library vs the top level app are from different files?

You can check this by browsing your phone storage in /data/data/your-package for the preference file for the top level app and the library. You might find that you have a different preference file for each, which I think means that you can't share prefs between the library / app.

You might be able to get around these limitations by only reading and writing to prefs from the top level app, and creating an interface to deliver those prefs to the library. If your library is simply presented with the values from the top level, then the library won't have to access the prefs, and thus all your preference access is done from a single place.

Also, this will allow you to have different preferences for full vs. free (which is the default behavior anyway, since they will be stored in separate preference files), and then you can send the proper info down to the lib based on version.

How to use SharedPreferences in Android to store, fetch and edit values

To obtain shared preferences, use the following method
In your activity:

SharedPreferences prefs = this.getSharedPreferences(
      "com.example.app", Context.MODE_PRIVATE);

To read preferences:

String dateTimeKey = "com.example.app.datetime";

// use a default value using new Date()
long l = prefs.getLong(dateTimeKey, new Date().getTime()); 

To edit and save preferences

Date dt = getSomeDate();
prefs.edit().putLong(dateTimeKey, dt.getTime()).apply();

The android sdk's sample directory contains an example of retrieving and storing shared preferences. Its located in the:

<android-sdk-home>/samples/android-<platformversion>/ApiDemos directory

Edit==>

I noticed, it is important to write difference between commit() and apply() here as well.

commit() return true if value saved successfully otherwise false. It save values to SharedPreferences synchronously.

apply() was added in 2.3 and doesn't return any value either on success or failure. It saves values to SharedPreferences immediately but starts an asynchronous commit.
More detail is here.

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