输出数组中元素个数为1 - lengh的全排列

public class Permutation2 {

	public void permutation(LinkedList list, String prefix) {
		if (!prefix.equals("")) {
			System.out.println(prefix);
		}
		for (int i = 0; i < list.size(); i++) {
			LinkedList temp = new LinkedList(list);
			permutation(temp, prefix + temp.remove(i).toString());
		}
	}
	public static void main(String[] args) {
		Permutation2 pta = new Permutation2();
		LinkedList list = new LinkedList();
		int[] a = { 1, 2, 3,4};
		for (int i : a) {
			list.add(i);
		}
		pta.permutation(list, "");
	}
}