“Warning: Do not place Android context classes in static fields; this is a memory leak (and also breaks Instant Run)”

Question

Similar question have been asked here, here and here but the context is quite different from this and moreover the code that gave from this error is written by the makers o

Answer 1

I ended up putting this in AppController which has no warning.

public class AppController extends MultiDexApplication {

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

    private static AppController mInstance;

    public static synchronized AppController getInstance() {
        return mInstance;
    }

    @Override
    public void onCreate() {
        super.onCreate();

        mInstance = this;

    }
}

So whenever you need it just call AppController.getContext()

Answer 2

This was my solution. There is no need to hold a static reference when you're just returning the instance of the RequestQueue?

public class VolleyRequestQueue {

    private static VolleyRequestQueue mInstance;
    private RequestQueue mRequestQueue;

    private VolleyRequestQueue() {

    }

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

    public RequestQueue getRequestQueue(Context context) {
        if(mRequestQueue == null) {
            mRequestQueue = Volley.newRequestQueue(context.getApplicationContext());
        }
        return mRequestQueue;
    }
}

Answer 3

I found the solution to this in the answer to a similar question answered by CommonsWare

I quote

The quoted Lint warning is not complaining about creating singletons. It is complaining about creating singletons holding a reference to an arbitrary Context, as that could be something like an Activity. Hopefully, by changing mContext = context to mContext = context.getApplicationContext(), you will get rid of that warning (though it is possible that this still breaks Instant Run — I cannot really comment on that).

Creating singletons is fine, so long as you do so very carefully, to avoid memory leaks (e.g., holding an indefinite static reference to an Activity).

So Google is not actually contracting itself. To fix this, if this.getApplicationContext is supplied as a parameter for the context, then there will be no memory leak.

So in essence, ignore the warning and supply this.getApplicationContext as a parameter for the context.