Java数组高效生成所有两位以上元素的组合：如何用递归实现排列组合？

import java.util.*;

public class CombinationPermutation {

    public static void main(String[] args) {
        int[] nums = {11, 33, 22};
        generateCombinations(nums);
    }

    public static void generateCombinations(int[] nums) {
        for (int i = 2; i <= nums.length; i++) {
            combine(nums, i, 0, new ArrayList<>(), new ArrayList<>());
        }
    }

    private static void combine(int[] nums, int k, int start, List<Integer> current, List<List<Integer>> result) {
        if (current.size() == k) {
            permute(current);
            return;
        }
        for (int i = start; i < nums.length; i++) {
            current.add(nums[i]);
            combine(nums, k, i + 1, current, result);
            current.remove(current.size() - 1);
        }
    }

    private static void permute(List<Integer> current) {
        Collections.sort(current);
        do {
            System.out.println(current);
        } while (Collections.nextPermutation(current));
    }
}