A map whose entries are sorted by their keys. All optional operations such as TreeMap.put(K, V) and TreeMap.remove(java.lang.Object) are supported.

This map sorts keys using either a user-supplied comparator or the key's natural order:

• User supplied comparators must be able to compare any pair of keys in this map. If a user-supplied comparator is in use, it will be returned by TreeMap.Comparator.
• If no user-supplied comparator is supplied, keys will be sorted by their natural order. Keys must be mutually comparable: they must implement Java.Lang.IComparable and Java.Lang.IComparable.compareTo(T) must be able to compare each key with any other key in this map. In this case TreeMap.Comparator will return null.

When the ordering is not consistent with equals the behavior of this class is well defined but does not honor the contract specified by Java.Util.IMap. Consider a tree map of case-insensitive strings, an ordering that is not consistent with equals:

TreeMap map = new TreeMap(String.CASE_INSENSITIVE_ORDER);
   map.put("a", "android");

   // The Map API specifies that the next line should print "null" because
   // "a".equals("A") is false and there is no mapping for upper case "A".
   // But the case insensitive ordering says compare("a", "A") == 0. TreeMap
   // uses only comparators/comparable on keys and so this prints "android".
   System.out.println(map.get("A"));
 

[Android Documentation]