java - How to retrieve a context from a non-activity class?

Question

I have found one answer that appears to say I should create a separate class and make a static MyApplication object and make a get method. Then any class can call MyApplication.get() to retrieve the context.

Is there any other cleaner way? This is my situation:

I have a class A and a class B. Class A contains an object from class B (let's call the object b). In class A I call, "b.play()". However, I get a null pointer exception because class B needs to pass a context to the MediaPlayer.create() method.

Until now I threw together a hack and from class A I called.... "b.play(this)" and simply passed the context to B. However that is pretty ugly and looks like a bad use of OOP.

Any thoughts?

Answer 1

This problem seem to arise a lot in Android development. One solution to obtaining a reference to a specific Context is subclassing the Application and grab a reference to the Context which you want.

public class MyApplication extends Application { 

private Context context;

@Override
public onCreate() {
  super.onCreate();
  this.context = getApplicationContext() // Grab the Context you want.
}

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

This solution however requires that you specify the name of your subclass in your manifest.

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

You can then use this anywhere in your application like this in non-activity classes.

MyApplication.getContext();  // Do something with the context! :)