I want to implement a class which will handle all HTTP Requests of my application, which will be basically:
You are not executing the task. You are just creating it. I think you need to make:
Get g = new Get();
g.execute();
But you are using the lifecycle of the task in a wrong way. OnPostExecute runs on the Main thread, where you should do all the updates as needed. You can pass the task a View for example.