In the App Engine docs, what is the ellipsis (JID...
) for in this method signature?
public MessageBuilder withRecipientJids(JID... recipientJids)
What's the function of those three dots?
Those are Java varargs. They let you pass any number of objects of a specific type (in this case they are of type JID).
In your example, the following function calls would be valid:
MessageBuilder msgBuilder; //There should probably be a call to a constructor here ;)
MessageBuilder msgBuilder2;
msgBuilder.withRecipientJids(jid1, jid2);
msgBuilder2.withRecipientJids(jid1, jid2, jid78_a, someOtherJid);
See more here: http://java.sun.com/j2se/1.5.0/docs/guide/language/varargs.html