Is there a way to make SharedPreferences global throughout my whole Android app?

Question

Is there a way to make SharedPreferences global throughout my whole app? Right now I'm using these lines in a lot of places throughout my code to store simple on/off settings for a number of preferences that my users can set. I just want to call them once globally if possible:

SharedPreferences settings = getSharedPreferences("prefs", 0);
SharedPreferences.Editor editor = settings.edit();

Any tips on how to be able to call just these line in all classes would be awesome:

editor.putString("examplesetting", "off");
editor.commit(); 

and

String checkedSetting = settings.getString("examplesetting", "");

Answer 1

I know, I know, I will get inflamed, and casted into the embers of hell....

Use a singleton class that wraps around the SharedPreference settings.. something like this:

public class PrefSingleton{
   private static PrefSingleton mInstance;
   private Context mContext;
   //
   private SharedPreferences mMyPreferences;

   private PrefSingleton(){ }

   public static PrefSingleton getInstance(){
       if (mInstance == null) mInstance = new PrefSingleton();
       return mInstance;
   }

   public void Initialize(Context ctxt){
       mContext = ctxt;
       //
       mMyPreferences = PreferenceManager.getDefaultSharedPreferences(mContext);
   }
}

And create wrapper functions around what your examples represented in the question, for example,

PrefSingleton.getInstance().writePreference("exampleSetting", "off");

and the implementation could be something like this:

// Within Singleton class

public void writePreference(String key, String value){
     Editor e = mMyPreference.edit();
     e.putString(key, value);
     e.commit();
}

From your first activity, activate the singleton class, in this manner, something like this:

PrefSingleton.getInstance().Initialize(getApplicationContext());

The reason I risk down-vote, is, using global static classes can be a bad idea and goes against the practice of programming fundamentals. BUT having said that, as nit-picky aside, it will ensure only the one and only object of the class PrefSingleton can exist and be accessible regardless of what activities the code is at.

Answer 2

I would extend Application and include the SharedPreferences.Editor as a field with a getter.

public class APP extends Application {
    private final SharedPreferences settings = getSharedPreferences("prefs", 0);
    private final SharedPreferences.Editor editor = settings.edit();

    public SharedPreferences.Editor editSharePrefs() {
        return editor;
    }
}

Then you can access it from any Activity with

((APP) getApplication()).editSharePrefs().putString("examplesetting", "off");
((APP) getApplication()).editsharePrefs().commit();

Alternatively, you could also throw in the method

    public static APP getAPP(Context context) {
        return (APP) context.getApplicationContext();
    }

Although, this would simply change the calls you make to

APP.getAPP(this).editSharePrefs().putString("examplesetting", "off");
APP.getAPP(this).editsharePrefs().commit();

So it really is a personal preference, which looks cleaner to you.