oib - validacija

public class oib {

    public static boolean checkOIB(String oib){

        if (oib.length() != 11) return false;

        try{
            Long.parseLong(oib);
        }catch (NumberFormatException e) {
            return false;
        }

        int a = 10;
        for (int i = 0; i < 10; i++)
        {
            a = a + Integer.parseInt(oib.substring(i, 1));
            a = a % 10;
            if (a == 0) a = 10;
            a *= 2;
            a = a % 11;
        }
        int kontrolni = 11 - a;
        if (kontrolni == 10) kontrolni = 0;

        return kontrolni == Integer.parseInt(oib.substring(10, 1));
    }

}