Volley Singleton class in android

Volley Singlton class in androidx 

public class SingleTask extends Application {

    private RequestQueue requestQueue;

    private static Context ctx;

    public RequestQueue getRequestQueue() {

        if (requestQueue == null) {

            // getApplicationContext() is key, it keeps you from leaking the

            // Activity or BroadcastReceiver if someone passes one in.

            requestQueue = Volley.newRequestQueue(ctx.getApplicationContext());

        }

        return requestQueue;

    }

    public <T> void addToRequestQueue(Request<T> req) {

        getRequestQueue().add(req);

    }

}