Best implementation for an isNumber(string) method

Question

In my limited experience, I\'ve been on several projects that have had some sort of string utility class with methods to determine if a given string is a number. The idea h

Answer 1

That's my implementation to check whether a string is made of digits:

public static boolean isNumeric(String string)
{
    if (string == null)
    {
        throw new NullPointerException("The string must not be null!");
    }
    final int len = string.length();
    if (len == 0)
    {
        return false;
    }
    for (int i = 0; i < len; ++i)
    {
        if (!Character.isDigit(string.charAt(i)))
        {
            return false;
        }
    }
    return true;
}