Method headMap

lib/java/util/TreeMap.java:1342–1350

Returns a sorted map over a range of this sorted map with all keys that are less than the specified endKey. Changes to the returned sorted map are reflected in this sorted map and vice versa. Note: The returned map will not allow an insertion of a key outside the specified range. @param

(K endKey)

     *             map and the specified key is outside of its range.
     */
    public SortedMap<K, V> headMap(K endKey) {
        // Check for errors
        if (comparator == null) {
            toComparable(endKey).compareTo(endKey);
        } else {
            comparator.compare(endKey, endKey);
        }
        return new SubMap<K, V>(this, endKey);
    }

    /**
     * Returns a set of the keys contained in this map. The set is backed by