error in obtaining int[] from a stream about 2122-s2

[DikshantDulal]

You don't need to collect it as a list. You can directly convert your Arrays.stream to int[] in the following manner.

int[] convert(int[] arr, Function<Integer, Integer> fn) {
return Arrays.stream(arr).map(x -> fn.apply(x)).toArray();
}

[Lucas-Wee]

my attempt is this:
Object[] obj_arr = {new Integer(1), new Integer(2), new Integer(3)};
List result = obj_arr.stream().flatMapToInt(x -> x.intValue()).boxed().collect(Collectors.collect())

[aldrichwilliams23]

Another implementation that's pretty similar to @DikshantDulal's is

int[] convert(int[] arr, Function<Integer, Integer> fn) {
Return IntStream.range(0, arr.length).map(x -> fn.apply(arr[x]).toArray());
}

Idea is to use IntStream to access certain positions in the array then go from there!

[coffeecode2]

yes, my implementation is similar to @aldrichwilliams23's implementation where you use an IntStream and apply map on it.