Java int[] array to HashSet<Integer>

Question

I have an array of int:

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

I need a typed set from it:

Set<Integer> s; 

If I do the following:

s = new HashSet(Arrays.asList(a)); 

it, of course, thinks I mean:

List<int[]> 

whereas I meant:

List<Integer> 

This is because int is a primitive. If I had used String, all would work:

Set<String> s = new HashSet<String>(     Arrays.asList(new String[] { "1", "2", "3" })); 

How to easily, correctly and succinctly go from:

A) int[] a... 

to

B) Integer[] a ... 

Thanks!

Answer 1

Using Stream:

// int[] nums = {1,2,3,4,5} Set<Integer> set = Arrays.stream(nums).boxed().collect(Collectors.toSet()) 

Answer 2

The question asks two separate questions: converting int[] to Integer[] and creating a HashSet<Integer> from an int[]. Both are easy to do with Java 8 streams:

int[] array = ... Integer[] boxedArray = IntStream.of(array).boxed().toArray(Integer[]::new); Set<Integer> set = IntStream.of(array).boxed().collect(Collectors.toSet()); //or if you need a HashSet specifically HashSet<Integer> hashset = IntStream.of(array).boxed()     .collect(Collectors.toCollection(HashSet::new));