kotlin reading from file into byte array

I found this worked nicely:

fun File.chunkedSequence(chunk: Int): Sequence<ByteArray> {
    val input = this.inputStream().buffered()
    val buffer = ByteArray(chunk)
    return generateSequence {
        val red = input.read(buffer)
        if (red >= 0) buffer.copyOf(red)
        else {
            input.close()
            null
        }
    }
}

Use it like this.

    file.chunkedSequence(CHUNK_SIZE).forEach {
        // Do something with `it`
    }

Not an exact match to your question but this is the question that came up when I was looking to chunk a file into a sequence of byte arrays.

The easiest way is to use

File("aaa").readBytes()

That one will read the whole file into the ByteArray. But you should carefully know you have enough RAM in the heap to do so

The ByteArray can be created via ByteArray(100) call, where 100 is the size of it

For the RandomAccessFile, it is probably better to use at the readFully function, which reads exactly the requested amount of bytes.

The classic approach is possible to read a file by chunks, e.g.

    val buff = ByteArray(1230)
    File("aaa").inputStream().buffered().use { input ->
      while(true) {
        val sz = input.read(buff)
        if (sz <= 0) break

        ///at that point we have a sz bytes in the buff to process
        consumeArray(buff, 0, sz)
      }
    }