public class PointLaterLength {

    public static void main(String[] args) {

        double ver = 123.321;

        String str = String.valueOf(ver);//将浮点数转变成字符串

        String[] arr = str.split("\\.");//切割字符串

        System.out.println(arr[1].length());//获取小数点后字符串长度

    }

}