Class DescendingMap

src/main/java/org/mapdb/BTreeMapJava.java:1091–1539

    }

    static protected  class DescendingMap<K,V> extends AbstractMap<K,V> implements  ConcurrentNavigableMap2<K,V> {

        protected final ConcurrentNavigableMapExtra<K,V> m;

        protected final K lo;
        protected final boolean loInclusive;

        protected final K hi;
        protected final boolean hiInclusive;

        public DescendingMap(ConcurrentNavigableMapExtra<K,V> m, K lo, boolean loInclusive, K hi, boolean hiInclusive) {
            this.m = m;
            this.lo = lo;
            this.loInclusive = loInclusive;
            this.hi = hi;
            this.hiInclusive = hiInclusive;
            if(lo!=null && hi!=null && m.comparator().compare(lo, hi)>0){
                throw new IllegalArgumentException();
            }


        }


/* ----------------  Map API methods -------------- */

        @Override
        public boolean containsKey(Object key) {
            if (key == null) throw new NullPointerException();
            K k = (K)key;
            return inBounds(k) && m.containsKey(k);
        }

        @Override
        public V get(Object key) {
            if (key == null) throw new NullPointerException();
            K k = (K)key;
            return ((!inBounds(k)) ? null : m.get(k));
        }

        @Override
        public V put(K key, V value) {
            checkKeyBounds(key);
            return m.put(key, value);
        }

        @Override
        public V remove(Object key) {
            K k = (K)key;
            return (!inBounds(k))? null : m.remove(k);
        }

        @Override
        public int size() {
            if(hi==null && lo==null)
                return m.size();

            Iterator<K> i = m.keyIterator(lo, loInclusive, hi, hiInclusive);