How to convert int[] into List<Integer> in Java?

Question

How do I convert int[] into List<Integer> in Java?

Of course, I'm interested in any other answer than doing it in a loop, item by item. But if there's no other answer, I'll pick that one as the best to show the fact that this functionality is not part of Java.

Answer 1

Streams

1. In Java 8+ you can make a stream of your int array. Call either Arrays.stream or IntStream.of.
2. Call IntStream#boxed to use boxing conversion from int primitive to Integer objects.
3. Collect into a list using Stream.collect( Collectors.toList() ). Or more simply in Java 16+, call Stream#toList().

Example:

int[] ints = {1,2,3}; List<Integer> list = Arrays.stream(ints).boxed().collect(Collectors.toList()); 

In Java 16 and later:

List<Integer> list = Arrays.stream(ints).boxed().toList();