I have a byte[] that I would like to represent as a List where the elements are the plain value of each individual byte, for example if I have
byte[] buf; //filled elsewhere
System.out.println(Arrays.toString(buf)); //prints [97, 99, -100]
I want to end up with an object equivalent to
new ArrayList<Long>{97, 99, -100};
How can I make this object from my original buf?
Java 8:
byte[] buf = { 97, 99, -100 };
List<Long> list = LongStream.range(0, buf.length).map(i -> buf[(int) i]).boxed().collect(Collectors.toList());
System.out.println(list);
output:
[97, 99, -100]
I can't think of any utility that can cast an array of one object type to a different object type. You can either get a List of bytes by using:
List<Byte> bytes = Arrays.asList(buf);
Or make your own utility method similar to:
public static List<Long> bytesToListOfLongs(byte[] bytes) {
List<Long> longs = new ArrayList<Long>();
longs.ensureCapacity(bytes.length);
for (byte b: bytes) {
longs.add(new Long(b));
}
return longs;
}
And later use it like:
byte[] buf; //filled elsewhere
List<Long> longs = bytesToListOfLongs(buf);
b in bytesToListOfLongs method to long as in (long)b might be necessary. It's a widening primitive conversion though, so I'm not sure about it and I can't test it at the moment.