只能迭代java.lang.Iterable的数组或实例吗？

Question

I try to forEach a 2d-list, that put a int [] array to lambda. The compiler complains "Can only iterate over an array or an instance of java.lang.Iterable"

    List<int []> list2d = new ArrayList<>();
    list2d.add(new int[] {1,3,5,7});
    list2d.add(new int[] {2,4,6,8});

    list.forEach((array)-> {        */// why here array can't be iterated?*
        for(int num: array) {
            System.out.println(num);
        }
    });

Answer 1

I tried it on my computer and it works but you need to use the correct variable in:

list.forEach((array)-> {        // why here array can't be iterated?
    for(int num: array) {
        System.out.println(num);
    }
});

you must iterate list2d not list, isn't it? Also, remember the comments in java are between /* */ or after // if is one line.

Answer 2

If I understood you correctly, you want to iterate over elements inside the array elements. You could achieve this with something like the following:

list2d.stream()
      .flatMapToInt( Arrays::stream )
      .forEach( System.out::println );