public static Stack<Integer> stack = new Stack<Integer>();

	private static List<String> listint = new ArrayList<String>();

	public static void main(String[] args) {

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

		for (int i = 2; i <= nums.length; i++) {

			groupData(nums, i, 0);

		}

	}

	private static void groupData(int[] nums, int targ, int cur) {

		// TODO Auto-generated method stub

		if (cur == targ) {

			Object[] shu1 = stack.toArray();

			Arrays.sort(shu1);

			if (!listint.contains(Arrays.toString(shu1))) {

				System.out.println(Arrays.toString(shu1));

			}

			listint.add(Arrays.toString(shu1));

			return;

		}

		for (int i = 0; i < nums.length; i++) {

			if (stack.contains(nums[i])) {

				continue;

			}

			stack.add(nums[i]);

			groupData(nums, targ, cur + 1);

			stack.pop();

		}

	}

输出：

[1, 2]
[1, 3]
[1, 4]
[2, 3]
[2, 4]
[3, 4]
[1, 2, 3]
[1, 2, 4]
[1, 3, 4]
[2, 3, 4]
[1, 2, 3, 4]