复数乘法

class Solution {
    public String complexNumberMultiply(String a, String b) {
        String x[] = a.split("\\+|i");
        String y[] = b.split("\\+|i");//分割字符串，以+和i为分隔符
        
        int a_r = Integer.parseInt(x[0]);//将字符串转化为数字
        int a_v = Integer.parseInt(x[1]);
        int b_r = Integer.parseInt(y[0]);
        int b_v = Integer.parseInt(y[1]);
        
        return (a_r*b_r - a_v*b_v) + "+" + (a_v*b_r + a_r*b_v) + "i";
    }
}