code: public synchronized void reset(MemoryLongArray longArray) throws IOException {
        _writer.flush();
        _writer.position(DATA_START_POSITION);
        for(int i = 0, cnt = longArray.length(); i < cnt; i++) {
            _writer.writeLong(longArray.get(i));
        }
        _writer.flush();
    }
docs: Resets this ArrayFile with the specified long array.
  
  @param longArray - the long array.
  @throws IOException