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kotlinlang

if I have to write a `ByteBuffer` to file, what's the best way? Using `InputStream` like here: <https://stackoverflow.com/questions/35528409/write-a-large-inputstream-to-file-in-kotlin>?

Embrace `java.nio`:

```
fun Path.channel(vararg options: OpenOption): FileChannel = FileChannel.open(this, *options)

fun main(args: Array&lt;String&gt;) {
    val buf: ByteBuffer = TODO()
    val file = Paths.get("output")

    file.channel(StandardOpenOption.CREATE, StandardOpenOption.WRITE).use { channel -&gt;
        while (buf.hasRemaining()) channel.write(buf)
    }
}
```

why ` while (buf.hasRemaining()) ` and not simply `channel.write(buf)`?

can it simply write an arbitrarly amount of bytes? Why?

Yes, `channel.write` may write only a portion of the buffer as per the Javadocs.

If you feed it a large buffer, it will only write as much as it can efficiently write in one go.

for which reason would it efficientely write only a portion?

`Channel` is a very generic interface. It might be a channel bound to a network socket, which only has a limited buffer. You can't just send out 500MB immediately, you have to wait for the network speed. So as long as the network buffer is full, it cannot write.

hi, just a quick question, this is valid also for reading I guess

```val buffer = FileChannel.open(path, StandardOpenOption.READ).use { channel -&gt;
            bufferBig(channel.size().i).also {
                while (channel.read(it) &gt; 0) Unit
            }
        }```

`read()` returns the number of bytes read