NavigableSet<String> stringSet = new TreeSet<String>();
Collections.addAll(stringSet, "abc", "cde", "x-ray" ,"zed");
String last = stringSet.floor("x-ray");
assert last.equals("x-ray");
String secondToLast =
last == null ? null : stringSet.lower(last);
String thirdToLast =
secondToLast == null ? null : stringSet.lower(secondToLast);
assert thirdToLast.equals("abc");
NavigableSet<String> headSet = stringSet.headSet(last, true);
NavigableSet<String> reverseHeadSet = headSet.descendingSet();
assert reverseHeadSet.toString().equals("[x-ray, cde, abc]");
String conc = " ";
for (String s : reverseHeadSet) {
conc += s + " ";
}
assert conc.equals(" x-ray cde abc ");
for (Iterator<String> itr = headSet.descendingIterator(); itr.hasNext(); ) {
itr.next(); itr.remove();
}
assert headSet.isEmpty();
