GenHashJava.java

String hashSequence = merchantKey + "|" + txnId + "|" + amount + "|" + productInfo + "|" + firstName + "|" + email + "|" +
        udf1 + "|" + udf2 + "|" + udf3 + "|" + udf4 + "|" + udf5 + "|" + "|" + "|" + "|" + "|" + "|" + salt;

public static String hashCal(String type, String hashString) {
	StringBuilder hash = new StringBuilder();
	MessageDigest messageDigest = null;
	try {
		messageDigest = MessageDigest.getInstance(type);
		messageDigest.update(hashString.getBytes());
		byte[] mdbytes = messageDigest.digest();
		for (byte hashByte : mdbytes) {
			 hash.append(Integer.toString((hashByte & 0xff) + 0x100, 16).substring(1));
		}
	} catch (NoSuchAlgorithmException e) {
		e.printStackTrace();
	}
	return hash.toString();
}