Your goal in this kata is to implement a difference function, which subtracts one list from another and returns the result.

It should remove all values from list a, which are present in list b keeping their order.

example:

Kata.arrayDiff(new int[] {1, 2}, new int[] {1}) => new int[] {2}

If a value is present in b, all of its occurrences must be removed from the other:

 

best solution:

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

public class Kata {
    public static int[] arrayDiff(int[] a, int[] b) {
        List<Integer> listA = Arrays.stream(a).boxed().collect(Collectors.toList());
        List<Integer> listB = Arrays.stream(b).boxed().collect(Collectors.toList());
        listA.removeAll(listB);
        return listA.stream().mapToInt(e -> e).toArray();
    }
}