Question

I have the following HashMap:

HashMap<String, Integer> counts = new HashMap<String, Integer>();

What is the simplest way to order it according to the values?

Answer 1

You can’t sort a Map by the values, especially not a HashMap, which can’t be sorted at all.

Instead, you can sort the entries:

List<Map.Entry<String, Integer>> entries = new ArrayList<Map.Entry<String, Integer>>(map.entrySet());
Collections.sort(entries, new Comparator<Map.Entry<String, Integer>>() {
  public int compare(
      Map.Entry<String, Integer> entry1, Map.Entry<String, Integer> entry2) {
    return entry1.getValue().compareTo(entry2.getValue());
  }
});

will sort the entries in ascending order of count.