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HowTo: Creating a Barcode in Kotlin Android

TL;DR

implementation 'com.google.zxing:core:3.4.0'

MainActivity.kt

main_activity.xml

Introduction

There are lots of articles and help online for producing an Android app that can scan barcodes (including the excellent KBarcode library and sample app developed by my colleague Alistair). However, it was harder to find much information about generating and displaying barcodes programmatically. Most articles appear to include either larger libraries or complete sample apps, rather than simple instructions. I needed to create a 1D (CODE 128) barcode in an Android app and so, turned to the ZXing project for help.

ZXing library

ZXing is a barcode image processing library originally released in 2008 and subsequently open-sourced and now hosted on Google Open Source. It was originally implemented in Java but has since been ported to many other languages and has support for 1D product, 1D industrial, and 2D barcodes.

The ZXing project has been on GitHub for years, its first release was over 5 years ago and has had 27 releases and over 3.5k commits at the time of writing! Although the project is now in maintenance mode it is used by over 17k projects and has been forked over 8k times.

The project consists of various components including an Android Barcode Scanning app, but for this blog, we just needed the core functionality. The code examples and a step-by-step guide for creating a new Android app that displays a 1D Code 128 barcode can be found below.

Step-by-Step Example (Android Studio 3.5)

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1. Create a new Android Studio project

a. Choose Empty Activity, click Next

b. Configure your project, click Next

c. Run the new project to ensure project setup is correct

2. Add the ZXing library

Edit app/build.gradle and add a dependency on ZXing core library

implementation 'com.google.zxing:core:3.4.0'

 

3. Set up a dimensions file

While not strictly necessary, it's useful to create a dimensions file to hold the size of your barcode image which can be accessed from the layout and from the code. Create the file app/src/main/res/values/dimens.xml with these values

 

4. Create the layout

Edit app/src/main/res/layout/activity_main.xml and replace the default TextView with an ImageView to hold the barcode and a TextView below it to hold the barcode value.

 

5. Edit MainActivity.kt

Edit the file MainActivity.kt (the directory location will vary depending on the package name chosen when creating the project in step 1b.)

a. Add a function to generate the barcode image

b. Add a helper method that sets the size of the barcode image and uses the previous function to set the actual barcode image, it also sets the text value

c. Finally, call the helper method from OnCreate. The whole MainActivity.kt should look like this

 

6. Re-run the app to see the final result!