Private enum constructor

Question

The constructor for this enum is private. What does that mean?

public enum SLocale {      EN_US(Locale.US, "www.abc.com", "www.edc.com", "www.vvv.com",             "www.earn.com");      List<String> domains;     Locale loc;     IMap map;      private SLocale(Locale loc, String... domains) {         this.domains = Arrays.asList(domains);         this.loc = loc;         this.siteMap = Factory.getMap(loc);     }      public List<String> getDomains() {         return domains;     }      public Locale getLoc() {         return loc;     }      public ISiteMap getMap() {         return map;     } } 

Answer 1

A private constructor only allows objects to be constructed from within the class definition. Being an enum, it is easy to get confused, so I usually find it easier to think of an enum as a class with some special features. So when you write:

SLocale.EN_US 

Basically, the parameters

Locale.US, "www.abc.com", "www.edc.com", "www.vvv.com", "www.earn.com" 

will be passed to the private constructor so that the enum can be instantiated. Enum constructors have to be private.

Answer 2

From: http://download.oracle.com/javase/tutorial/java/javaOO/enum.html

Note: The constructor for an enum type must be package-private or private access. It automatically creates the constants that are defined at the beginning of the enum body. You cannot invoke an enum constructor yourself.

You cannot actually have a public enum constructor.