As simple as it comes. java autoboxing.

        for(int i=0;i<b.length;i++){
            bytes.add(b[i]);
        }

Latest addition

I recently used Arrays.asList() and found that if its parameter is a basic type array, this is the error message;

Multiple markers at this line
    - The method addAll(Collection<? extends Byte>) in the type ArrayList<Byte> is not applicable for the arguments 
     (List<byte[]>)

In other words, it treats the basic type array as a List<type[]>, that is, as a whole object.

Another modification method is to change byte[] to Byte[], so that it can run normally. In other words, the parameter received by asList() should be an object array;
If the parameter is an array of basic types, it will be treated as an object array with only one element (that is, the element is an array of basic types).