有没有方法可以解决这种交换失败的问题？

代码写的没问题~

public int[] swap(int []arr) {

int temp;

int a ,b;

a=arr[0]; b=arr[1];

System.out.println("交换前a和b的值为：" + a + "," + b);

temp = a;

a = b;

b = temp;

System.out.println("交换后a和b的值为：" + a + "," + b);

int arr1[] = { a, b };

return arr1;

}

public static void main(String[] args) {

ExchangeDemo ed = new ExchangeDemo();

int[] arr = { 4, 5 };

System.out.println("交换前m和n的值为：" + arr[0] + "," + arr[1]);

int[] arr1=ed.swap(arr);

System.out.println("交换后m和n的值为：" + arr1[0] + "," + arr1[1]);

}