Private variables/methods in anonymous class?

Question

I have created an anonymous class in which I declare a few variables and methods. My java teacher tells me to make these private. I don't see how changing the modifier makes any difference since these variables and methods are private to the anonymous class anyway, so I prefer to have no modifier at all. Who is right and what makes more sense? See below for example code where I choose no modifier for 'map' and 'convert' rather than making them private.

Collections.sort(list, new Comparator<String>(){
  public int compare(String a, String b){
    return convert(a).compareTo(convert(b));
  }
  Map<String, String> map = new HashMap<String, String>();
  String convert(String s) {
    String u = map.get(s);
    if (u == null)
      map.put(s, u = s.toUpperCase());
    return u;
  }
});

Answer 1

I would be tempted to make them private simply for the fact that if you refactor the code and pull the anonymous class out as a standard class (Intellij, for example, can do this at the click of a button), having private fields is what you really want. You won't have to go and rework your classes to match your standard.