When all the keys of a Map are values from the same enum, the ``++Map++`` can be replaced with an ``++EnumMap++``, which can be much more efficient than other sets because the underlying data structure is a simple array.
== Noncompliant Code Example
----
public class MyClass {
public enum COLOR {
RED, GREEN, BLUE, ORANGE;
}
public void mapMood() {
Map<COLOR, String> moodMap = new HashMap<COLOR, String> ();
== Compliant Solution
EnumMap<COLOR, String> moodMap = new EnumMap<> (COLOR.class);