集合相关操作

int[]转换List

int[] nums = {1,2,3,4};

List<Integer> collect = 
Arrays.stream(nums1).boxed().collect(Collectors.toList());

交换某两个位置的数据

Collections.swap(vector, 0, 4);
Before swap: [1, 2, 3, 4, 5]
After swap: [5, 2, 3, 4, 1]