Creating a byte[] from a List<Byte>

Question

What is the most efficient way to do this?

Answer 1

byte[] byteArray = new byte[byteList.size()];
for (int index = 0; index < byteList.size(); index++) {
    byteArray[index] = byteList.get(index);
}

You may not like it but that’s about the only way to create a Genuine™ Array® of byte.

As pointed out in the comments, there are other ways. However, none of those ways gets around a) creating an array and b) assigning each element. This one uses an iterator.

byte[] byteArray = new byte[byteList.size()];
int index = 0;
for (byte b : byteList) {
    byteArray[index++] = b;
}