How to use

fastIterator

method

in

it.unimi.dsi.fastutil.objects.Reference2ReferenceMaps

/**
 * Returns a hash code for this map.
 *
 * The hash code of a map is computed by summing the hash codes of its entries.
 *
 * @return a hash code for this map.
 */
@Override
public int hashCode() {
  int h = 0, n = size();
  final ObjectIterator<Reference2ReferenceMap.Entry<K, V>> i = Reference2ReferenceMaps.fastIterator(this);
  while (n-- != 0)
    h += i.next().hashCode();
  return h;
}
@Override

  @Override
  public String toString() {
    final StringBuilder s = new StringBuilder();
    final ObjectIterator<Reference2ReferenceMap.Entry<K, V>> i = Reference2ReferenceMaps.fastIterator(this);
    int n = size();
    Reference2ReferenceMap.Entry<K, V> e;
    boolean first = true;
    s.append("{");
    while (n-- != 0) {
      if (first)
        first = false;
      else
        s.append(", ");
      e = i.next();
      if (this == e.getKey())
        s.append("(this map)");
      else
        s.append(String.valueOf(e.getKey()));
      s.append("=>");
      if (this == e.getValue())
        s.append("(this map)");
      else
        s.append(String.valueOf(e.getValue()));
    }
    s.append("}");
    return s.toString();
  }
}

/** {@inheritDoc} */
@SuppressWarnings({"unchecked", "deprecation"})
@Override
public void putAll(final Map<? extends K, ? extends V> m) {
  if (m instanceof Reference2ReferenceMap) {
    ObjectIterator<Reference2ReferenceMap.Entry<K, V>> i = Reference2ReferenceMaps
        .fastIterator((Reference2ReferenceMap<K, V>) m);
    while (i.hasNext()) {
      final Reference2ReferenceMap.Entry<? extends K, ? extends V> e = i.next();
      put(e.getKey(), e.getValue());
    }
  } else {
    int n = m.size();
    final Iterator<? extends Map.Entry<? extends K, ? extends V>> i = m.entrySet().iterator();
    Map.Entry<? extends K, ? extends V> e;
    while (n-- != 0) {
      e = i.next();
      put(e.getKey(), e.getValue());
    }
  }
}
/**