How to get activity context into a non-activity class android?

Question

I have a Activity class from where I am passing some information to a helper class(Non-activity) class. In the helper class I want to use the getSharedPreferences(). But I am unable to use it as it requires the activity context.

here is my code:

  class myActivity extends Activity
    {
    @Override
        protected void onCreate(Bundle savedInstanceState) 
        {

            // TODO Auto-generated method stub
            super.onCreate(savedInstanceState);
            setContentView(R.layout.home);


            Info = new Authenticate().execute(ContentString).get();
            ItemsStore.SetItems(Info);

        }

    }

class ItemsStore
{
  public void SetItems(Information info)
 {
  SharedPreferences  localSettings = mContext.getSharedPreferences("FileName", Context.MODE_PRIVATE);
            SharedPreferences.Editor editor = localSettings.edit();
            editor.putString("Url", info.Url);
            editor.putString("Email", info.Email);
 }
}

ANy idea how this can be achieved?

Answer 1

Instead of creating memory leaks (by holding activity context in a class field) you can try this solution because shared preferences do not need activity context but ... any context :) For long living objects you should use ApplicationContext.

Create the application class:

public class MySuperAppApplication extends Application {
    private static Application instance;

    @Override
    public void onCreate() {
        super.onCreate();
        instance = this;
    }

    public static Context getContext() {
        return instance.getApplicationContext();
    }
}

Register it at manifest

<application
    ...
    android:name=".MySuperAppApplication" >
    ...
</application>

Then you can do something like this

public void persistItems(Information info) {
    Context context = MySuperAppApplication.getContext();
    SharedPreferences sharedPreferences = context.getSharedPreferences("urlPersistencePreferences", Context.MODE_PRIVATE);
    sharedPreferences.edit()
        .putString("Url", info.Url)
        .putString("Email", info.Email);
}

Method signature looks better this way because it does not need external context. This can be hide under some interface. You can also use it easily for dependency injection.

HTH