use for loop to visit all elements in a HashSet (Java)?

Question

I have write the code as:

public class Solution {
    public int[] intersection(int[] nums1, int[] nums2) {
        HashSet<Integer> has1 = new HashSet(Arrays.asList(nums1)); 
        for (int i: has1)
            System.out.println(i);
        return nums1;
    }
}

num1: [1,2,4,2,3]
num2: [4,5,6,3]

On the for loop it says java.lang.ClassCastException: [I cannot be cast to java.lang.Integer

Answer 1

you cannot do this directly but you need to prefer a indirect approach

int[] a = { 1, 2, 3, 4 };
        Set<Integer> set = new HashSet<>();
        for (int value : a) {
            set.add(value);
        }
        for (Integer i : set) {
            System.out.println(i);
        }

using Java 8

 1) Set<Integer> newSet = IntStream.of(a).boxed().collect(Collectors.toSet());//recomended

    2)  IntStream.of(a).boxed().forEach(i-> System.out.println(i)); //applicable

here first foreach is sufficient for you and If you want to go by set, go with second for loop

Answer 2

您的集合包含Integer对象，因此在foreach循环中进行迭代时，应编写for (Integer i : collection) -这是因为基本类型int没有自己的Iterator实现。