为什么它给我java.lang.ArrayIndexOutOfBoundsException？

Question

交换最后两个数字，给出ArrayIndexOutOfBoundException ... 因为我是编程新手并且无法找到问题，请纠正我在哪里做错了... 提前谢谢你......

public static void main(String[] args) {

    Scanner scan = new Scanner(System.in);

    System.out.println("Enter the Number : ");
    int n = scan.nextInt();
    int m = n;
    int size = String.valueOf(n).length();

    int arr[] = new int[size];

    for (int i = 0; i < size; i++) {
        arr[i] = n % 10;
        n = n / 10;
    }

    System.out.println("The next permuatation will be : ");

    int temp = arr[m - 2];
    arr[m - 2] = arr[m - 1];
    arr[m - 1] = temp;

    System.out.print(arr);
}