List<Integer>、Integer[]、int[] 转换

    int[] data = {4,5,6,7,8};

    // int[]转List<Integer>
    List<Integer> list1 = Arrays.stream(data).boxed().collect(Collectors.toList());

    // int[]转Integer[]
    Integer[] integers1 = Arrays.stream(data).boxed().toArray(Integer[]::new);

    //List<Integer> 转int[]
    int[] arr1 = list1.stream().mapToInt(Integer::valueOf).toArray();

    //List<Integer> Integer[]
    Integer[] integers2 = list1.toArray(new Integer[0]);

    //Integer[] 转int[]
    int[] arr2 = Arrays.stream(integers1).mapToInt(Integer::valueOf).toArray();

    //Integer[] 转 List<Integer>
    List<Integer> list2 = Arrays.asList(integers1);