I've seen the discussion at [this][1] question regarding how a class that implements from an interface would be instantiated. In my case, I'm writing a very small program in Java that uses an instance of `TreeMap`, and according to everyone's opinion there, it should be instantiated like:

    Map<X> map = new TreeMap<X>();

In my program, I'm calling the function `map.pollFirstEntry()`, which is not declared in the `Map` interface (and a couple others who are present in the `Map` interface too). I've managed to do this by casting to a `TreeMap<X>` everywhere I call this method like: 

    someEntry = ((TreeMap<X>) map).pollFirstEntry();

I understand the advantages of the initialization guidelines as described above for large programs, however for a very small program where this object would not be passed to other methods, I would think it is unnecessary. Still, I'm writing this sample code as part of a job application, and I don't want my code to look badly nor cluttered. What would be the most elegant solution?

  [1]: http://stackoverflow.com/questions/383947/what-does-it-mean-to-program-to-an-interface