CODEWITHSUNDEEP
android
Flarosa
Flarosa

Reputation: 1861

Working with Singletons (Context issue)

I'm in the process of porting an iOS project to Android. The iOS project makes use of several key singletons to provide global resources for the application, such as a database and an set of web services. Many of these singletons use resources such as files, network, or shared preferences.

I'm running into a lot of problems trying to port this to Android, because I often require a "Context" object when I am writing singleton code that is not part of an Activity. I can usually pass in a Context when I first construct the singleton, but I have heard that I should not store this as a member variable because it could cause memory leaks.

What is the best way to deal with this issue?

Upvotes: 1

Views: 1345

Answers (2)

Kashan Danish
Kashan Danish

Reputation: 155

If you HAVE to keep singletons in app, you can pass context to method of singleton which uses context

In MySingleton.java

public class MySingleton {
   //private instance, private constructor and getInstance() goes here

   public void doSomething(Context context, int foo, int bar) {
       //Use context
   }
}

Calling from Activity/Service

MySingleton.getInstance().doSomething(this, 1, 2);

Calling from Fragments

MySingleton.getInstance().doSomething(getActivity, 1, 2);

If you can afford changing architecture, please steer clear of singletons. You can use dependency injection as an alternative. This is how you do it.

Upvotes: 1

CommonsWare
CommonsWare

Reputation: 1006869

I can usually pass in a Context when I first construct the singleton, but I have heard that I should not store this as a member variable because it could cause memory leaks.

Use the Application object, which you get from getApplication() (on Activity) or getApplicationContext() (on any other Context). This is itself a singleton, and so it is pre-leaked and cannot be leaked further.

Note, though that the Application object is not a suitable Context for anything closely tied to the UI (e.g., inflating layouts); such things should not be in singletons in general.

See Dave Smith's epic blog post on the roles of different types of Context for more details.

Upvotes: 1

Related Questions