Question

I wanted to know what is the best approach for sharing singleton in my android app.
I have a few activities that does not rely on each other, but I want them to have a singleton that they can all read/write.

Where should I place it?

Thanks

Answer 1

Your application should be a singleton. It avoids many other problem related to sharing datas or models.

In your manifest.xml :

<application android:icon="@drawable/icon"
    android:label="@string/app_name" android:debuggable="false"
    android:name="<class of your application see below>" 
            android:launchMode="singleTop">
 ..... all activities/services/receivers/etc... as usual

</application>

And your android:name refers to this class :

public class MyApp extends Application {
//singleton, but use onCreate more than constructor to build shared resources.
....
}//class

And then, from within any activity, you can retrieve your singleton to get shared resources by doing this :

((MyApp)getApplicationContext()).getSharedResources()....

or

MyApp.getInstance().getSharedResources()....

Having a singleton as a app is a usual design pattern in android, it is especially useful to handle device rotation (as it tends to destroy activities and recreate them) as it provides a stable entity to persist during app lifecycle.