Java Checksum Calculate calcChecksum(String value, int length)

Description

calc Checksum

License

Apache License

Declaration

public static char calcChecksum(String value, int length) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

public class Main {
    public static char calcChecksum(String value, int length) {
        if (value != null && value.length() == length + 1) {
            value = value.substring(0, length);
        }//ww w .  j a v  a 2s .  c o m
        if (value == null || value.length() != length) {
            throw new IllegalArgumentException(
                    "Illegal size of value; must be either" + length + " or " + (length + 1) + " characters");
        }
        int oddsum = 0;
        int evensum = 0;
        for (int i = value.length() - 1; i >= 0; i--) {
            if ((value.length() - i) % 2 == 0) {
                evensum += Character.digit(value.charAt(i), 10);
            } else {
                oddsum += Character.digit(value.charAt(i), 10);
            }
        }
        int check = 10 - ((evensum + 3 * oddsum) % 10);
        if (check >= 10)
            check = 0;
        return Character.forDigit(check, 10);
    }
}

Related

1. calcChecksum(byte[] buffer, int offset, int length)
2. calcChecksum(byte[] buffer, int start, int end)
3. calcCheckSum(byte[] bytes, int num)
4. calcCheckSum(byte[] data, int offset, int maxIdx)
5. calculateChecksum(InputStream is, String algorithm)
6. calculateChecksums(Optional zos, InputStream inputStream, Set checksumAlgorithms)
7. checkSum(boolean[] a)
8. checkSum(byte abyte0[])