该方法
printPermutation是递归的核心。它不能正确捕获 开始 和 结束 索引。这很重要，因为您正在尝试分块交换
进行以下更改应使其起作用。
public static void main(String[] args) { char a[]= "123".toCharArray(); printPermutation(a, 0, a.length);}private static void printPermutation(char[] a, int startIndex, int endIndex) { if (startIndex == endIndex)//reached end of recursion, print the state of a System.out.println(new String(a)); else { //try to move the swap window from start index to end index //i.e 0 to a.length-1 for (int x = startIndex; x < endIndex; x++) { swap(a, startIndex, x); printPermutation(a, startIndex + 1, endIndex); swap(a, startIndex, x); } }}private static void swap(char[] a, int i, int x) { char t = a[i]; a[i] = a[x]; a[x] = t;}
