Re: Using java.util.map

I sincerely hope I'm missing something about how java.util.map can be
used, but it seems that there is no way to update a single value
without traversing the map twice, at least not cleanly. As an
example, consider this code taken from the Sun autoboxing example:

public static void main(String[] args) {
  Map<String, Integer> m = new TreeMap<String, Integer>();
  for (String word : args) {
    Integer freq = m.get(word);
    m.put(word, (freq == null ? 1 : freq + 1));
  }
}

Notice how both get() and put() are invoked. Clearly this means that
the map is traversed twice - once to find the value, and once to
figure out where to put a new value (which happens to be the same
place!). In C++ (where I come from), maps contain objects of type
pair<key, value>, and one can therefore retrieve the pair<> in
question and update the value with only one traversal of the map. Is
there any way to avoid two traversals in Java short of writing a kludgy
wrapper object such as

class WrapsAnInt {
  private int wrapped;

  public WrapsAnInt( int w ) { wrapped = w; }
  public void setWrapped( int w ) { wrapped = w; }
  public int getWrapped() { return wrapped; }
}

and put *those* in the map? If not, why didn't Java simply introduce
the concept of a pair<> like C++ did and fix the problem?