package eu.simuline.util;
   
   
   import java.util.List;
   import java.util.ArrayList;
   import java.util.Set;
   import java.util.SortedSet;
  import java.util.AbstractSet;
  import java.util.Collection;
  import java.util.AbstractCollection;
  import java.util.SortedMap;
  import java.util.Map;
  import java.util.Map.Entry;
  import java.util.Comparator;
  import java.util.Iterator;
  import java.util.ListIterator;
  import java.util.Objects;
  
  /**
   * A {@link SortedMap} with ordering 
   * given by the ordering by which the keys are added. 
   * This is the {@link Map} corresponding with {@link ListSet}. 
   * <p>
   * Did not use {@link java.util.AbstractMap}, 
   * e.g. because {@link #keySet()} shall return more than just a {@link Set}. 
   *
   * @param <K>
   *    the class of keys for this map. 
   * @param <V>
   *    the class of values for this map. 
   *
   * @author <a href="mailto:ernst.reissner@simuline.eu">Ernst Reissner</a>
   * @version 1.0
   */
  public final class ListMap<K, V> implements SortedMap<K, V> {
  
      /* -------------------------------------------------------------------- *
       * Inner classes.                                                       *
       * -------------------------------------------------------------------- */
  
      /**
       * Class of entries of the encylosing map. 
       * **** I wonder whether there is no generic implementation 
       * for {@link java.util.Map.Entry}. 
       */
      private final class Entry implements Map.Entry<K, V> {
  
  	/* ------------------------------------------------------------------ *
  	 * fields.                                                            *
  	 * ------------------------------------------------------------------ */
  
  	/**
  	 * The key of this entry. 
  	 * The corresponding value is {@link #value}. 
  	 */
  	private final K key;
  
  	/**
  	 * The value of this entry corresponding with the key {@link #key}. 
  	 * Note that in contrast to the key, 
  	 * the value of this entry may be changed 
  	 * (through {@link #setValue(Object)}). 
  	 */
  	private V value;
  
  	/* ------------------------------------------------------------------ *
  	 * constructors.                                                      *
  	 * ------------------------------------------------------------------ */
  
  	/**
  	 * Creates a new entry for the enclosing map 
  	 * defined by the given <code>key</code> and <code>value</code>. 
  	 */
  	private Entry(K key, V value) {
  	    this.key = key;
  	    this.value = value;
  	}
  
  	/* ------------------------------------------------------------------ *
  	 * methods.                                                           *
  	 * ------------------------------------------------------------------ */
  
  	/**
  	 * Returns the {@link #key} of this entry. 
  	 */
  	public K getKey() {
  	    return this.key;
  	}
  
  	/**
  	 * Returns the {@link #value} of this entry. 
  	 */
  	public V getValue() {
  	    return this.value;
  	}
  
  	/**
 	 * Sets a new {@link #value} of this entry 
 	 * and returns the original one. 
 	 */
 	public V setValue(V value) {
 	    V oldValue = this.value;
 	    this.value = value;
 	    return oldValue;
 	}
 
 	// fits with method equals 
 	public int hashCode() {
 	    return this.getKey().hashCode() + this.getValue().hashCode();
 	}
 
 	// **** seems to be a bug in javadoc 
 	/**
 	 * Returns whether <code>obj</code> equals this entry, 
 	 * i.e. whether <code>obj</code> 
 	 * is an instance of {@link java.util.Map.Entry} 
 	 * and both, its key and its value equals key and value of this entry. 
 	 * Note that both, key and value may be <code>null</code>. 
 	 */
 	public boolean equals(Object obj) {
 	    if (!(obj instanceof Map.Entry)) {
 		return false;
 	    }
 
 	    Map.Entry<?, ?> other = (Map.Entry<?, ?>) obj;
 	    return Objects.equals(this.getKey(),   other.getKey()) 
 		&& Objects.equals(this.getValue(), other.getValue());
 	}
 
     } // class Entry
 
     /**
      * Represents the key set of the enclosing map 
      * given by {@link ListMap#keySet()}. 
      * <p>
      * Like base class {@link AbstractSet}, 
      * this class supports neither {@link Set#add(Object)} 
      * nor {@link Set#addAll(Collection)}, 
      * i.e. those methods throw an {@link UnsupportedOperationException}. 
      * In contrast, this class supports methods 
      * {@link Set#clear()}, 
      * {@link Set#remove(Object)}, 
      * {@link Set#removeAll(Collection)} and 
      * {@link Set#retainAll(Collection)}. 
      * The iterator returned by {@link #iterator()} 
      * supports {@link Iterator#remove()}. 
      *
      * @see ListMap#keysSet
      */
     private class Keys extends AbstractSet<K> implements SortedSet<K> {
 
 	/* ------------------------------------------------------------------ *
 	 * methods implementing Set based on AbstractSet.                     *
 	 * ------------------------------------------------------------------ */
 
 	/**
 	 * Returns actually an instance of {@link ListMap.KeysIterator}. 
 	 */
         public Iterator<K> iterator() {
             return new KeysIterator();
         }
 
 	/**
 	 * Returns actually the size of the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#size()}. 
 	 */
 	public int size() {
 	    return ListMap.this.size();
         }
 
 	/**
 	 * Returns actually whether <code>obj</code> 
 	 * is a key of the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#containsKey(Object)}. 
 	 */
         public boolean contains(Object obj) {
 	    return ListMap.this.containsKey(obj);
         }
 
 	/**
 	 * Interpretes <code>obj</code> as key 
 	 * of the enclosing {@link ListMap} 
 	 * and removes the according key-value pair if present. 
 	 * Returns whether the according key-value pair was present 
 	 * when invoking this method using 
 	 * {@link ListMap#removeIdx(int)}. 
 	 */
          public boolean remove(Object obj) {
 	    int idx = ListMap.this.keys.getList().indexOf(obj);
 	    return ListMap.this.removeIdx(idx);
         }
 
 	/**
 	 * Clears actually the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#clear()}. 
 	 */
         public void clear() {
             ListMap.this.clear();
 	}
 
 	/* ------------------------------------------------------------------ *
 	 * methods implementing SortedSet.                                    *
 	 * ------------------------------------------------------------------ */
 
 	public Comparator<? super K> comparator() {
 	    return ListMap.this.comparator();
 	}
 
 	public K first() {
 	    return ListMap.this.keys.first();
 	}
 
 	public K last() {
 	    return ListMap.this.keys.last();
 	}
 
 	public SortedSet<K> subSet(K fromElement, K toElement) {
 	    return ListMap.this.subMap(fromElement, toElement).keySet();
 	}
 
 	public SortedSet<K> headSet(K toElement) {
 	    return ListMap.this.headMap(toElement).keySet();
 	}
 
 	public SortedSet<K> tailSet(K fromElement) {
 	    return ListMap.this.tailMap(fromElement).keySet();
 	}
 
     } // class Keys 
 
     /**
      * Class of iterator of class  {@link ListMap.Keys}. 
      *
      * @see ListMap.Keys#iterator()
      */
     private class KeysIterator extends XIterator implements Iterator<K> {
     	public K next() {
             return this.lIter.next();
         }
     } //  class KeysIterator
 
 
     /**
      * Represents the set of entries of the enclosing map 
      * given by {@link ListMap#entrySet()}. 
      * <p>
      * Like base class {@link AbstractSet}, 
      * this class supports neither {@link Set#add(Object)} 
      * nor {@link Set#addAll(Collection)}, 
      * i.e. those methods throw an {@link UnsupportedOperationException}. 
      * In contrast, this class supports methods 
      * {@link Set#clear()}, 
      * {@link Set#remove(Object)}, 
      * {@link Set#removeAll(Collection)} and 
      * {@link Set#retainAll(Collection)}. 
      * The iterator returned by {@link #iterator()} 
      * supports {@link Iterator#remove()}. 
      *
      * @see ListMap#entrySet
      */
     private class Entries
 	extends  AbstractSet<Map.Entry<K, V>> 
 	implements SortedSet<Map.Entry<K, V>> {
 
 	/* ------------------------------------------------------------------ *
 	 * methods implementing Set based on AbstractSet.                     *
 	 * ------------------------------------------------------------------ */
 
 	/**
 	 * Returns actually an instance of {@link ListMap.EntriesIterator}. 
 	 */
         public Iterator<Map.Entry<K, V>> iterator() {
             return new EntriesIterator();
 	}
 
 	/**
 	 * Returns actually the size of the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#size()}. 
 	 */
         public int size() {
 	    return ListMap.this.size();
         }
 
 	/**
 	 * Assumes that <code>obj</code> is a {@link java.util.Map.Entry} 
 	 * and returns its key. 
 	 *
 	 * @throws NullPointerException 
 	 *    if <code>obj</code> is <code>null</code>. 
 	 * @throws ClassCastException 
 	 *    if <code>obj</code> is neither <code>null</code> 
 	 *    nor an instance of {@link java.util.Map.Entry}. 
 	 */
 	private Object getKey(Object obj) {
 	    Map.Entry<?, ?> entry = (Map.Entry<?, ?>) obj;
 	    return entry.getKey();
 	}
 
 	/**
 	 * Returns actually whether <code>obj</code> 
 	 * is an instance of {@link java.util.Map.Entry} 
 	 * with a key contained in the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#containsKey(Object)}. 
 	 */
         public boolean contains(Object obj) {
 	    if (!(obj instanceof Map.Entry)) {
 		return false;
 	    }
 	    return ListMap.this.containsKey(getKey(obj));
         }
 
 	/**
 	 * Removes <code>obj</code> from the entry set if present 
 	 * and returns whether it was present. 
 	 * Effectively checks whether <code>obj</code> 
 	 * is an instance of {@link java.util.Map.Entry}. 
 	 * If not returns <code>false</code>. 
 	 * If it is an instance of {@link java.util.Map.Entry}
 	 * removes the according key-value pair 
 	 * from the enclosing {@link ListMap} if present. 
 	 * Returns whether <code>obj</code>'s key was present 
 	 * when invoking this method. 
 	 * This is done 
 	 * invoking {@link ListMap.Keys#remove(Object)}. 
 	 */
         public boolean remove(Object obj) {
 	    if (!(obj instanceof Map.Entry)) {
 		return false;
 	    }
 	    Map.Entry<?, ?> entry = (Map.Entry<?, ?>) obj;
 	    entry.getClass().getTypeParameters();
 	    return ListMap.this.keysSet.remove(getKey(entry));
         }
 
 	/**
 	 * Clears actually the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#clear()}. 
 	 */
         public void clear() {
 	    ListMap.this.clear();
  	}
 
 	/* ------------------------------------------------------------------ *
 	 * methods implementing SortedSet.                                    *
 	 * ------------------------------------------------------------------ */
 
 	public Comparator<? super Map.Entry<K, V>> comparator() {
 	    return new  Comparator<Map.Entry<K, V>>() {
 		public int compare(Map.Entry<K, V> entry1, 
 				   Map.Entry<K, V> entry2) {
 		    return ListMap.this.comparator()
 			.compare(entry1.getKey(), entry2.getKey());
 		}
 	    };
 	}
 
 	private Map.Entry<K, V> key2entry(K key) {
 	    return new ListMap<K, V>.Entry(key, get(key));
 	}
 
 	public Map.Entry<K, V> first() {
 	    return key2entry(ListMap.this.keys.first());
 	}
 
 	public Map.Entry<K, V> last() {
 	    return key2entry(ListMap.this.keys.last());
 	}
 
 	public SortedSet<Map.Entry<K, V>> subSet(Map.Entry<K, V> fromElement, 
 					         Map.Entry<K, V>   toElement) {
 	    return ListMap.this.subMap(fromElement.getKey(),
 				       toElement  .getKey()).entrySet();
 	}
 
 	public SortedSet<Map.Entry<K, V>> headSet(Map.Entry<K, V>  toElement) {
 	    return ListMap.this.headMap(toElement  .getKey()).entrySet();
 	}
 
 	public SortedSet<Map.Entry<K, V>> tailSet(Map.Entry<K, V> fromElement) {
 	    return ListMap.this.tailMap(fromElement.getKey()).entrySet();
 	}
 
     } // class Entries 
 
     /**
      * Class of iterator of class  {@link ListMap.Entries}. 
      *
      * @see ListMap.Entries#iterator()
      */
     private class EntriesIterator extends XIterator 
 	implements Iterator<Map.Entry<K, V>> {
 
     	public Map.Entry<K, V> next() {
 	    int idx = this.lIter.nextIndex();
 	    return new Entry(this.lIter.next(), 
 			     ListMap.this.values.get(idx));
         }
     } //  class EntriesIterator
 
     /**
      * Represents the values collection of the enclosing map 
      * given by {@link ListMap#values()}. 
      * <p>
      * Like base class {@link AbstractCollection}, 
      * this class supports neither {@link Collection#add(Object)} 
      * nor {@link Collection#addAll(Collection)}, 
      * i.e. those methods throw an {@link UnsupportedOperationException}. 
      * In contrast, this class supports methods 
      * {@link Set#clear()}, 
      * {@link Collection#remove(Object)}, 
      * {@link Collection#removeAll(Collection)} and 
      * {@link Collection#retainAll(Collection)}. 
      * The iterator returned by {@link #iterator()} 
      * supports @link Iterator#remove()}. 
      *
      * @see ListMap#valuesColl
      */
     private class Values extends AbstractCollection<V> {
 
 	/**
 	 * Returns actually an instance of {@link ListMap.ValuesIterator}. 
 	 */
         public Iterator<V> iterator() {
             return new ValuesIterator();
         }
 
 	/**
 	 * Returns actually the size of the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#size()}. 
 	 */
         public int size() {
 	    return ListMap.this.size();
         }
 
 	/**
 	 * Returns actually whether <code>obj</code> 
 	 * is a value of the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#containsValue(Object)}. 
 	 */
         public boolean contains(Object obj) {
 	    return ListMap.this.containsValue(obj);
 	}
 
 	/**
 	 * Interpretes <code>obj</code> as value 
 	 * of the enclosing {@link ListMap} 
 	 * and removes the first according key-value pair if present. 
 	 * Returns whether the according key-value pair was present 
 	 * when invoking this method invoking using 
 	 * {@link ListMap#removeIdx(int)}. 
 	 */
         public boolean remove(Object obj) {
 	    int idx = ListMap.this.values.indexOf(obj);
 	    return ListMap.this.removeIdx(idx);
         }
 
 	/**
 	 * Clears actually the enclosing {@link ListMap} 
 	 * delegating to {@link ListMap#clear()}. 
 	 */
           public void clear() {
 	    ListMap.this.clear();
 	}
 
     } // class Values 
 
     /**
      * Class of iterator of class  {@link ListMap.Values}. 
      *
      * @see ListMap.Values#iterator()
      */
     @edu.umd.cs.findbugs.annotations.SuppressWarnings
 	(value = "RV_RETURN_VALUE_IGNORED_NO_SIDE_EFFECT", 
 	 justification = "bug in findbugs")
     private class ValuesIterator extends XIterator implements Iterator<V> {
   	public V next() {
 	    int idx = this.lIter.nextIndex();
             this.lIter.next(); // has side effect! 
 	    return ListMap.this.values.get(idx);
         }
     } //  class ValuesIterator
 
     /**
      * Common superclass of iterators on key set, 
      * value collection and entries set 
      * providing all methods but {@link Iterator#next()}. 
      * Implementation is based on a {@link ListIterator}. 
      */
     private abstract class XIterator {
 
 	/* ------------------------------------------------------------------ *
 	 * fields.                                                            *
 	 * ------------------------------------------------------------------ */
 
 	/**
 	 * An iterator over the list view of the key set 
 	 * of the enclosing {@link ListMap}. 
 	 *
 	 * @see ListMap#keys
 	 * @see ListSet#getList()
 	 */
 	@SuppressWarnings("checkstyle:visibilitymodifier")
 	protected final ListIterator<K> lIter;
 
 	/* ------------------------------------------------------------------ *
 	 * constructors.                                                      *
 	 * ------------------------------------------------------------------ */
 
 	/**
 	 * Creates a pre-iterator. 
 	 *
 	 * @see ListMap#keys
 	 * @see ListSet#getList()
 	 */
 	XIterator() {
 	    this.lIter = ListMap.this.keys.getList().listIterator();
 	}
 
 	/* ------------------------------------------------------------------ *
 	 * methods.                                                           *
 	 * ------------------------------------------------------------------ */
 
 	/**
 	 * Returns whether the iterators based on this class 
 	 * has a next value. 
 	 *
 	 * @see Iterator#hasNext()
 	 */
     	public boolean hasNext() {
             return this.lIter.hasNext();
         }
     	//public abstract X next();
 
 	/**
 	 * Removes from the underlying collection the last element returned 
 	 * by the iterator based on this class.	
 	 *
 	 * @see Iterator#remove()
 	 */
     	public void remove() {
 	    // get the index of the element returned by next() last 
 	    int idxPrev = this.lIter.previousIndex();
 	    if (idxPrev == -1) {
 		// never called next() 
 		throw new IllegalStateException();
 	    }
 	    ListMap.this.removeIdx(idxPrev);
         }
     } //  class XIterator
 
     /* -------------------------------------------------------------------- *
      * fields.                                                              *
      * -------------------------------------------------------------------- */
 
     /**
      * The set of keys of this <code>ListMap</code>. 
      */
     private final ListSet<K> keys;
 
     /**
      * The values of this map. 
      * The according keys are in {@link #keys}. 
      */
     private final List<V> values;
 
     /**
      * The collection of values of this map returned by {@link #values()}. 
      * Note that each <code>ListMap</code> has a single values collection. 
      */
     private final Collection<V> valuesColl;
 
     /**
      * The set of keys of this map returned by {@link #keySet()}. 
      * Note that each <code>ListMap</code> has a single key set. 
      */
     private final SortedSet<K> keysSet;
 
     /**
      * The set of entries of this map returned by {@link #entrySet()}. 
      * Note that each <code>ListMap</code> has a single entry set. 
      */
     private final SortedSet<Map.Entry<K, V>> entrySet;
 
     /* -------------------------------------------------------------------- *
      * constructors and auxiliary methods.                                  *
      * -------------------------------------------------------------------- */
 
     /**
      * Creates an empty list map with key set 'ordered as added' 
      * as described by {@link ListSet#sortedAsAdded()}. 
      */
     public ListMap() {
 	this(ListSet.sortedAsAdded(), new ArrayList<V>());
     }
 
     /**
      * Creates an list map with the same key-value pairs as <code>map</code> 
      * and with ordering 'as added'. 
      * If no additional keys are added, this reflects the ordering 
      * given by iterating through the key set of <code>map</code>. 
      *
      * @see #map2keys(Map)
      * @see #map2values(Map)
      */
     public ListMap(Map<K, V> map) {
 	this(map2keys(map), map2values(map));
     }
 
     /**
      * Returns the key set of <code>map</code> as a <code>ListSet</code> 
      * with ordering 'ordered as added' 
      * as given by {@link ListSet#sortedAsAdded()}. 
      * This ordering reflects the ordering 
      * given by the iteration on the key set of <code>map</code>. 
      */
     private static <K, V> ListSet<K> map2keys(Map<K, V> map) {
 	ListSet<K> res = ListSet.sortedAsAdded();
 	res.addAll(map.keySet());
 	return res;
     }
 
     /**
      * Returns the value collection of <code>map</code> as a <code>List</code> 
      * with ordering 
      * given by the iteration on the key set of <code>map</code>. 
      * Note that there is no documentation **** 
      * that this ordering is the same as the one 
      * of the value collection {@link Map#values() map#values()}. **** 
      */
     private static <K, V> List<V> map2values(Map<K, V> map) {
 	List<V> res = new ArrayList<V>();
 	// **** using entrySet() would be more elegant, 
 	// but seems not to guarantee an ordering of iteration. 
 	for (K key : map.keySet()) {
 	    res.add(map.get(key));
 	}
 	return res;
     }
 
     /**
      * Creates a list map defined by the given keys and values 
      * <code>keys</code> and <code>values</code>. 
      * A key and a value correspond iff their index coincides. 
      * Thus <code>keys</code> and <code>values</code> must have the same size. 
      * Note that the entries of <code>keys</code> differ pairwise, 
      * whereas this is not necessary for <code>values</code>. 
      *
      * @param keys
      *    the set of keys as a {@link ListSet}. 
      * @param values
      *    the collection of according values as a {@link List} 
      *    with the same size as <code>keys</code>. 
      * @throws IllegalArgumentException
      *    if <code>keys</code> and <code>values</code> differ in size. 
      */
     private ListMap(ListSet<K> keys, List<V> values) {
 	if (keys.size() != values.size()) {
 	    throw new IllegalArgumentException
 		("Collection of keys and values must have same size. ");
 	}
 
 	this.keys       = keys;
 	this.values     = values;
 	this.valuesColl = new Values();
 	this.keysSet    = new Keys();
 	this.entrySet   = new Entries();
     }
 
     /* -------------------------------------------------------------------- *
      * Methods.                                                             *
      * -------------------------------------------------------------------- */
 
     public void clear() {
 	this.keys  .clear();
 	this.values.clear();
     }
 
     public boolean containsKey(Object key) {
 	return this.keys.contains(key);
     }
 
     public boolean containsValue(Object val) {
 	return this.values.contains(val);
     }
 
     public SortedSet<Map.Entry<K, V>> entrySet() {
 	return this.entrySet;
     }
 
     public V get(Object key) {
 	int idx = this.keys.getList().indexOf(key);
 	if (idx == -1) {
 	    return null;
 	}
 	assert idx >= 0 && idx < size();
 	return this.values.get(idx);
     }
 
     public boolean isEmpty() {
 	assert this.keys.isEmpty() == this.values.isEmpty();
 	return this.keys.isEmpty();
     }
 
     public SortedSet<K> keySet() {
 	return this.keysSet;
     }
 
     public V put(K key, V value) {
 	int idx = this.keys.getList().indexOf(key);
 	if (idx == -1) {
 	    // Here, key is to be added 
 	    this.keys.getList().add(key);
 	    this.values.add(value);
 	    return null;
 	}
 	assert idx >= 0 && idx < size();
 
 	return this.values.set(idx, value);
     }
 
     public void putAll(Map<? extends K, ? extends V> other) {
 	Iterator<? extends K> iter = other.keySet().iterator();
 	K key;
 	while (iter.hasNext()) {
 	    key = iter.next();
 	    this.put(key, other.get(key));
 	}
     }
 
     public V remove(Object key) {
 	int idx = this.keys.getList().indexOf(key);
 	if (idx == -1) {
 	    return null;
 	}
 	assert idx >= 0 && idx < size();
 	V res = this.values.get(idx);
 	this.keys.getList().remove(idx);
 	this.values.remove(idx);
 	return res;
     }
 
     private boolean removeIdx(int idx) {
 	if (idx == -1) {
 	    return false;
 	}
 	assert idx >= 0 && idx < size();
 	this.keys.getList().remove(idx);
 	this.values.remove(idx);
 	return true;
     }
 
     public int size() {
 	return this.keys.size();
     }
 
     public Comparator<? super K> comparator() {
 	return this.keys.comparator();
     }
 
     public Collection<V> values() {
 	return this.valuesColl;
     }
 
     // also throws correct exception 
     public K firstKey() {
 	return keySet().first();
     }
 
    // also throws correct exception 
     public K lastKey() {
 	return keySet().last();
     }
 
     // better removed because easy to mix up with other methods 
     // offering just a view, not a copy of part of this map 
     // public Map<K,V> subMap(Set<K> someKeys) {
     // 	V val;
     // 	ListMap<K, V> res = new ListMap<K, V>();
     // 	for (K key : someKeys) {
     // 	    val = get(key);
     // 	    res.put(key, val);
     // 	}
     // 	return res;
     // }
 
     public ListMap<K, V> headMap(K toKey) {
 	return subMap(0, this.keys.obj2idx(toKey));
     }
 
     public ListMap<K, V> tailMap(K fromKey) {
  	return subMap(this.keys.obj2idx(fromKey), size());
     }
 
 
     @SuppressWarnings("checkstyle:genericwhitespace")
     ListMap<K, V> subMap(int fromIdx, int toIdx) {
 	ListSet<K> subKeys   = this.keys  .subSetIdx(fromIdx, toIdx);
 	List   <V> subValues = this.values.subList  (fromIdx, toIdx);
 
 	return new ListMap<K, V>(subKeys, subValues);
     }
 
     public ListMap<K, V> subMap(K fromKey, K toKey) {
 	return subMap(this.keys.obj2idx(fromKey), this.keys.obj2idx(toKey));
     }
 
     public boolean equals(Object obj) {
 	if (!(obj instanceof Map)) {
 	    return false;
 	}
 
 	Map<?, ?> other = (Map<?, ?>) obj;
 	return this.entrySet().equals(other.entrySet());
     }
 
     public int hashCode() {
 	return this.entrySet().hashCode();
     }
 
     public String toString() {
 	StringBuffer result = new StringBuffer();
 	result.append("<ListMap>\n");
 	for (int i = 0; i < size(); i++) {
 	    result.append("[" + this.keys.getList().get(i) 
 			  + " => " + this.values.get(i) + "]\n");
 	}
 	result.append("</ListMap>\n");
 
 	return result.toString();
     }
 
     public static void main(String[] args) {
 	List<Integer> list = new ArrayList<Integer>();
 	//list.add(0);
 	list.iterator().remove();
     }
 }