java 多个数 组合成不同的组

        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]