How to validate Fund ISIN Code

Below is a Java code to validate fund ISIN code..

import java.util.regex.Pattern;


public class TestISINCode{

public static void main(String args[]){

System.out.println(TestISINCode.checkIsinCode("GB00B0XWN709"));

}

private static final Pattern ISIN_PATTERN = Pattern.compile("[A-Z]{2}([A-Z0-9]){9}[0-9]");



public static boolean checkIsinCode(String isin) {

if (isin == null) {

return false;

}

if (!ISIN_PATTERN.matcher(isin).matches()) {

return false;

}



StringBuffer digits = new StringBuffer();

for (int i = 0; i < 11; i++) {

digits.append(Character.digit(isin.charAt(i), 36));

}

digits.reverse();

int sum = 0;

for (int i = 0; i < digits.length(); i++) {

int digit = Character.digit(digits.charAt(i), 36);

if (i % 2 == 0) {

digit *= 2;

}

sum += digit / 10;

sum += digit % 10;

}



int checkDigit = Character.digit(isin.charAt(11), 36);

int tensComplement = (sum % 10 == 0) ? 0 : ((sum / 10) + 1) * 10 - sum;

return checkDigit == tensComplement;

}

}