solution to issue iluwatar#602. Implemented multiton with enum, added example to app.java, a test for the enum, and commented my code

Author: anthonycampbell

multiton/src/main/java/com/iluwatar/multiton/App.java

@@ -31,9 +31,12 @@
  * pattern defines many globally accessible objects. The client asks for the correct instance from
  * the Multiton by passing an enumeration as parameter.
  * <p>
- * In this example {@link Nazgul} is the Multiton and we can ask single {@link Nazgul} from it using
- * {@link NazgulName}. The {@link Nazgul}s are statically initialized and stored in concurrent hash
- * map.
+ * There is more than one way to implement the multiton design pattern. In the first example
+ * {@link Nazgul} is the Multiton and we can ask single {@link Nazgul} from it using {@link NazgulName}.
+ * The {@link Nazgul}s are statically initialized and stored in concurrent hash map.
+ * <p>
+ * In the enum implementation {@link NazgulEnum} is the multiton. It is static and mutable because
+ * of the way java supports enums.
  *
  */
 public class App {
@@ -46,6 +49,7 @@ public class App {
    * @param args command line args
    */
   public static void main(String[] args) {
+    // eagerly initialized multiton
     LOGGER.info("KHAMUL={}", Nazgul.getInstance(NazgulName.KHAMUL));
     LOGGER.info("MURAZOR={}", Nazgul.getInstance(NazgulName.MURAZOR));
     LOGGER.info("DWAR={}", Nazgul.getInstance(NazgulName.DWAR));
@@ -55,5 +59,16 @@ public static void main(String[] args) {
     LOGGER.info("ADUNAPHEL={}", Nazgul.getInstance(NazgulName.ADUNAPHEL));
     LOGGER.info("REN={}", Nazgul.getInstance(NazgulName.REN));
     LOGGER.info("UVATHA={}", Nazgul.getInstance(NazgulName.UVATHA));
+    
+    // enum multiton
+    LOGGER.info("KHAMUL={}", NazgulEnum.KHAMUL);
+    LOGGER.info("MURAZOR={}", NazgulEnum.MURAZOR);
+    LOGGER.info("DWAR={}", NazgulEnum.DWAR);
+    LOGGER.info("JI_INDUR={}", NazgulEnum.JI_INDUR);
+    LOGGER.info("AKHORAHIL={}", NazgulEnum.AKHORAHIL);
+    LOGGER.info("HOARMURATH={}", NazgulEnum.HOARMURATH);
+    LOGGER.info("ADUNAPHEL={}", NazgulEnum.ADUNAPHEL);
+    LOGGER.info("REN={}", NazgulEnum.REN);
+    LOGGER.info("UVATHA={}", NazgulEnum.UVATHA);
   }
 }