The key is boxed() the IntStream into a Stream<Integer>, then only convert to an Array.

package com.mkyong;
import java.util.Arrays;
import java.util.stream.IntStream;
import java.util.stream.Stream;
public class StreamExample {
    public static void main(String[] args) {
        //int[] -> IntStream -> Stream<Integer> -> Integer[]
        int[] num = {3, 4, 5};
        //1. int[] -> IntStream
        IntStream stream = Arrays.stream(num);
        //2. IntStream -> Stream<Integer>
        Stream<Integer> boxed = stream.boxed();
        //3. Stream<Integer> -> Integer[]
        Integer[] result = boxed.toArray(Integer[]::new);
        System.out.println(Arrays.toString(result));
        // one line
        Integer[] oneLineResult = Arrays.stream(num).boxed().toArray(Integer[]::new);
        System.out.println(Arrays.toString(oneLineResult));

Output

[3, 4, 5]
[3, 4, 5]