public BufferedReadOnlyIterator(int fromIndex){
  _externalIteratorExhausted=true;
  _externalIterator=null;
  _bufferIterator=_buffer.listIterator(fromIndex);
}

public BufferedReadOnlyIterator ( int fromIndex ) { _externalIteratorExhausted = true ; _externalIterator = null ; _bufferIterator = _buffer . listIterator ( fromIndex ) ; }
create an iterator which starts directly iterating over the buffer , thus skipping the external storage .
