Class UnmodifiableSortedSet

lib/java/util/Collections.java:1423–1457

    }

    private static class UnmodifiableSortedSet<E> extends UnmodifiableSet<E>
            implements SortedSet<E> {
        private static final long serialVersionUID = -4929149591599911165L;

        private final SortedSet<E> ss;

        UnmodifiableSortedSet(SortedSet<E> set) {
            super(set);
            ss = set;
        }

        public Comparator<? super E> comparator() {
            return ss.comparator();
        }

        public E first() {
            return ss.first();
        }

        public SortedSet<E> headSet(E before) {
            return new UnmodifiableSortedSet<E>(ss.headSet(before));
        }

        public E last() {
            return ss.last();
        }

        public SortedSet<E> subSet(E start, E end) {
            return new UnmodifiableSortedSet<E>(ss.subSet(start, end));
        }

        public SortedSet<E> tailSet(E after) {
            return new UnmodifiableSortedSet<E>(ss.tailSet(after));
        }
    }

    private Collections() {
        /* empty */