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

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);

}

3 years ago

In Java 8 you can do this

int[] ints = {1,2,3};

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

3 years ago

Streams
In Java 8+ you can make a stream of your int array. Call either Arrays.stream or IntStream.of.
Call IntStream#boxed to use boxing conversion from int primitive to Integer objects.
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();

3 years ago