ISBN.java

import java.util.Scanner;
import java.util.Arrays;

public class ISBN {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner input = new Scanner(System.in);
        Character countryCode;
        String publisherCode;
        String bookCode;
        String uniqueCode;
        String[] arrISBN;
        int sumOfISBN;
        int validasi;

        System.out.println("Masukan kode kelompok negara (1 karakter):");
        countryCode = input.nextLine().charAt(0);

        System.out.println("Masukan kode penerbit (4 karakter):");
        publisherCode = input.nextLine();

        if (publisherCode.length() > 4) {
            String cutPublisherCode = publisherCode.substring(0, 4);
            publisherCode = cutPublisherCode;
        }

        System.out.println("Masukan kode unik buku (4 karakter):");
        bookCode = input.nextLine();

        if (bookCode.length() > 4) {
            String cutbookCode = bookCode.substring(0, 4);
            bookCode = cutbookCode;
        }

        arrISBN = buildISBNArray(countryCode, publisherCode, bookCode);
        sumOfISBN = getSumOfISBN(arrISBN);
        uniqueCode = Integer.toString(sumOfISBN % 11);
        validasi = validasiISBN(arrISBN, sumOfISBN, Integer.parseInt(uniqueCode));

        System.out.println();
        System.out.println("ISBN nya adalah: ");
        System.out.println(countryCode+"-"+publisherCode+"-"+bookCode+"-"+uniqueCode);
        System.out.println();
        System.out.println(sumOfISBN+" mod 11 = "+(validasi % 11)+" atau "+sumOfISBN+" = "+(validasi % 11)+" (mod 11)");
    }

    public static String[] buildISBNArray(Character countryCode, String publisherCode, String bookCode){
        String[] arrCountryCode = new String[1];
        arrCountryCode[0] = Character.toString(countryCode);
        String[] arrPublisherCode = publisherCode.split("");
        String[] arrBookCode = bookCode.split("");
        String[] arrISBN = concatAll(arrCountryCode, arrPublisherCode, arrBookCode);

        return arrISBN;
    }

    public static int validasiISBN(String[] arrISBN, int sumOfISBN, int uniqueCode){
        return sumOfISBN + ((arrISBN.length + 1) * uniqueCode);
    }

    public static int getSumOfISBN(String[] arrISBN){

        int i, sum = 0;

        for(i=0; i<arrISBN.length; i++){
            sum = sum + ((i+1) * Integer.parseInt(arrISBN[i]));
        }

        return sum;
    }

    public static <T> T[] concatAll(T[] first, T[]... rest) {
        int totalLength = first.length;
        for (T[] array : rest) {
            totalLength += array.length;
        }
        T[] result = Arrays.copyOf(first, totalLength);
        int offset = first.length;
        for (T[] array : rest) {
            System.arraycopy(array, 0, result, offset, array.length);
            offset += array.length;
        }
        return result;
    }
}