The following example is in CollationElementIterator and assumes that the Collator.getInstance return type is RuleBasedCollator. This assumption is never valid.

  String testString = "This is a test";
  RuleBasedCollator ruleBasedCollator = (RuleBasedCollator)Collator.getInstance();
  CollationElementIterator collationElementIterator = ruleBasedCollator.getCollationElementIterator(testString);
  int primaryOrder = CollationElementIterator.primaryOrder(collationElementIterator.next());

The API doc should clarify that it's usable only with RuleBasedCollator. Actually, CollationElementIterator should have never been public.