自己实现String 转化int

public static void main(String[] args) {
    String s = new String("664");
    byte[] strings = s.getBytes();
    int sum = 0;
    for (int i = strings.length; i > 0; i--) {
        int temp =strings[strings.length-i]-48;
        sum += temp*Math.pow(10, i - 1);
    }
    System.out.println(sum);
}