gistfile1.txt

public class ISBNreader {

    public  boolean isValid(String string) {
        String n2 = string.replaceAll("-", "");

        int result = 0;

        if (n2.length() != 10) {
            return false;
        }

        int counter = 10;

        for (int i = 0; i < 10; i++) {
            char j = n2.charAt(i);

            try{

                int x = j - '0';

                result += counter * x;

            }
            catch (Exception e){
                if (j != 'X' && i != 9){
                    return false;
                }
                result += 10;
            }

            counter -= 1;
        }

        return result % 11 == 0;
    }

}