What is the Best way to convert List<Byte> to List<Integer>

Question

Which is the best method to convert Currently I am using something like below

List<Byte> bytes = new ArrayList<Byte>();
List<Object> integers = Arrays.asList(bytes.toArray());

Then each object inside integers needs to be typecast to Integer. Is there any other way in which I can achieve this?

Answer 1

With the standard JDK, here's how to do it

List<Byte> bytes = new ArrayList<Byte>();
// [...] Fill the bytes list somehow

List<Integer> integers = new ArrayList<Integer>();
for (Byte b : bytes) {
  integers.add(b == null ? null : b.intValue());
}

If you're sure, you don't have any null values in bytes :

for (byte b : bytes) {
  integers.add((int) b);
}

Answer 2

If Google's Guava available in your project:

// assume listofBytes is of type List<Byte>
List<Integer> listOfIntegers = Ints.asList(Ints.toArray(listOfBytes));