Sample Demonstrating a Custom Token Validator with an Interface

// This code returns true if the generated token begins
// with two digits.
// If it returns false, CT-V will generate a new token.
public class ValidateToken implements ITokenValidator
{
    @Override
    public Boolean isValid( String value ) throws TokenException
    {
        int digit = value.charAt( 0 ) - '0';
        boolean even = digit % 2 == 0;
        if( even )
        {
            digit = value.charAt( 1 ) - '0';
            even = digit % 2 == 0;
            if( !even )
            {
                System.out.println( "First is even, second is odd. Really not okay." );
                return false;
            }
            System.out.println( "Yeah, it's ok." );
            return true;
        }
        else
        {
            System.out.println( "No, it's not even." );
            return false;
        }
    }
}