if (f != null && f._prev == null && f._revision == _revision)
if (f != null && f._revision == _revision)
            public boolean hasNext()            {                if (field != null) return true;                while (i < _fields.size())                {                    Field f = (Field) _fields.get(i++);                    if (f != null && f._prev == null && f._revision == _revision)                    {                        field = f;                        return true;                    }                }                return false;            }