为什么这不起作用?
public class AddArray
{
    public static void main(String[] args) 
    {
        int[] x = {1,2,3};
        int[] y = {1,2,3};
        dd(x,y);
        public static void add(int[]a, int[]b)
        {
            int[] sum = new int[a.length];
            for (int i=0; i<a.length; i++)
                sum[i] = a[i] + b[i];
            for (int i=0; i<a.length; i++)
                System.out.println(sum[i]);
        }
    }
}