java.util.Collections contains these static methods to construct SortedXXX:

SortedSet<T> unmodifiableSortedSet(SortedSet<T> s)
SortedMap<K,V> unmodifiableSortedMap(SortedMap<K, ? extends V> m)
SortedSet<T> synchronizedSortedSet(SortedSet<T> s)
SortedMap<K,V> synchronizedSortedMap(SortedMap<K,V> m)
SortedSet<E> checkedSortedSet(SortedSet<E> s, Class<E> type)
SortedMap<K,V> checkedSortedMap(SortedMap<K, V> m, Class<K> keyType,
                                Class<V> valueType)

Now that SortedXXX is more or less obsoleted by NavigableXXX, we
should provide analogues of the above for NavigableSet and NavigableMap.