# Android Development: Generating an EAN13 Barcode

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## Introduction

The European Article Number, or EAN, is a standard European barcode which is designed to encode the identification of a product and its manufacturer and is a superset of the American standard, UPC. The format of the EAN13 barcode encodes a string of 12 characters followed by a 13th character which acts as the control number and is calculated through a formula based on the first 12 characters.

Nowadays, barcodes are used everywhere. If you earn a living as a programmer, sooner or later the need of support of barcodes in your applications will come up. For example, it may be supermarket bonus system, where user is identified by barcode from his phone to get discount, or such payment systems as Starbucks moble payment network. In this article will be explained how to generate EAN13 barcodes on Android screen.

## EAN13 Calculation Basics

EAN13 barcode uses  a 12 digits product code, the thirteenth digit is a control number, which is calculated on the basis of first 12 digits. Calculation of control number ( digits numbered from right to left ) looks like this:

• P1 = the sum of even digits
• P2 = the sum of odd digits
• Z = P1 + 3 * P2
• R = the number divisible by 10 immediately superior to Z
• Control number = R – Z

Next, let’s see on EAN13 encoding system:

• The first digit is not encoded
• Each 6 following digit is encoded according to the first digit
• The 6 last digits are converted by the strict rule
 First digit Left 6 digits Right 6 digits 0 LLLLLL RRRRRR 1 LLGLGG RRRRRR 2 LLGGLG RRRRRR 3 LLGGGL RRRRRR 4 LGLLGG RRRRRR 5 LGGLLG RRRRRR 6 LGGGLL RRRRRR 7 LGLGLG RRRRRR 8 LGLGGL RRRRRR 9 LGGLGL RRRRRR

Encoding for the digits:

 Digit L – code G – code R – code 0 0001101 0100111 1110010 1 0011001 0110011 1100110 2 0010011 0011011 1101100 3 0111101 0100001 1000010 4 0100011 0011101 1011100 5 0110001 0111001 1001110 6 0101111 0000101 1010000 7 0111011 0010001 1000100 8 0110111 0001001 1001000 9 0001011 0010111 1110100