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

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();

There is no shortcut for converting from int[] to List<Integer> as Arrays.asList does not deal with boxing and will just create a List<int[]> which is not what you want. You have to make a utility method.

int[] ints = {1, 2, 3};
List<Integer> intList = new ArrayList<Integer>(ints.length);
for (int i : ints)
{
    intList.add(i);
}

Also from guava libraries... com.google.common.primitives.Ints:

List<Integer> Ints.asList(int...)