http://ec2-52-27-141-35.us-west-2.compute.amazonaws.com/problem/55b5147a56481b5f1661d8ba https://leetcode.com/problems/valid-number/

Doubles.java

public class Doubles {

    public Double parse(String s) {
        if (isNumber(s)) {
            return Double.valueOf(s);
        } else {
            return null;
        }
    }
  
    public boolean isNumber(String s) {
        try {
            Double.valueOf(s);
            if (s.charAt(s.length() - 1) == 'f' || s.charAt(s.length() - 1) == 'F' || s.charAt(s.length() - 1) == 'd' || s.charAt(s.length() - 1) == 'D') {
                return false;
            }
            return true;
        } catch (NumberFormatException e) {
            return false;
        }
    }
}