Я прочитал комментарий к transferFrom
FileChannel
* <p> This method is potentially much more efficient than a simple loop
* that reads from the source channel and writes to this channel. Many
* operating systems can transfer bytes directly from the source channel
* into the filesystem cache without actually copying them. </p>
Что это значит
Many operating systems can transfer bytes directly from the source channel
into the filesystem cache without actually copying them.
Если я читаю из канала, а затем записываю его в другой канал, разве он не передает байты в кеш?