Barcode4j - Generate check digit in an EAN13 barcode

Question

When yo generate a barcode with Barcode4j as an image, you could obtain the human readable text, too, for instance:

EAN13 barcode example

In this picture we can see that the human readable text is: 1000000012026

In this example the barcode has been generated with the code 100000001202 and the number 6 is the check digit added by Barcode4j generator.

So, my question is: Is possible obtain the check digit of an EAN13 generated barcode with Barcode4j? Because I know how to render this as a image, but I don't know how to obtain the human readable text, as a plain text.

Regards,

Miguel.

Answer 1

Thanks to Barcode4j plugin, you can calculate the checksum with the barcode format you need. In Java 7, you can calculate the checkSum as this way:

private String calculateCodeWithcheckSum(String codigo){
   EAN13Bean generator = new EAN13Bean();
   UPCEANLogicImpl impl = generator.createLogicImpl();
   codigo += impl.calcChecksum(codigo);
   return codigo;
}

First, you need the EAN13 barcode format, so you can get the class that the plugin provides you, and call its only method: createLogicImpl().

This method is used to give you a class of type UPCEANLogicImpl. This is the class you need, because you can find in it the method to calculate the checkSum. So, you only have to call the method calcChecksum giving your code (100000001202), and will give you the checkSum value (6).

You can check it in the next web: http://www.gs1.org/check-digit-calculator

Adding your code and the checkSum value will give you the value you need (1000000012026)

Answer 2

In case you what to compute the check digit without importing a java library here's the code:

public static String ean13CheckDigit(String barcode) {
    int s = 0;
    for (int i = 0; i < 12; i++) {
        int c = Character.getNumericValue(barcode.charAt(i));
        s += c * ( i%2 == 0? 1: 3);
    }
    s = (10 - s % 10) % 10;
    barcode += s;
    return barcode;
}