How do I find out if first character of a string is a number?

Question

In Java is there a way to find out if first character of a string is a number?

One way is

string.startsWith("1")

and do the above all the way till 9, but that seems very inefficient.

Edit: After the answer, I found out a regex way to do this as well:

s.substring(0,1).matches("[0-9]")

Answer 1

Character.isDigit(string.charAt(0));

Note that this will allow any Unicode digit, not just 0-9. You might prefer:

char c = string.charAt(0);
isDigit = (c >= '0' && c <= '9');

Edit: However, I neglected to mention that with either of these, you must first be sure that the string isn't empty. If it is, charAt(0) will throw a StringIndexOutOfBoundsException. startsWith does not have this problem.