Q: What's Codename One? How Does it Work?

Codename One is an open-source cross-platform Write Once Run Anywhere (WORA) framework to build native apps for iOS, Android, Desktop and Web with Java or Kotlin. The core appeal is its unrestricted access to the native platform allowing developers to write native code directly from Java or Kotlin and access everything that the native mobile platform can provide. You can generates native OS binaries that you can upload to Apple/Google etc. To understand how Codename One works, check the <a href="https://www.codenameone.com/introduction.html">introduction</a> or this <a href="https://stackoverflow.com/questions/10639766/how-does-codename-one-work/10646336#10646336">stackoverflow answer</a>. | Notice that Codename One works with IntelliJ/IDEA, Eclipse, VSCode and NetBeans. To understand Codename One's history, basics, features etc in detail, check <a href="https://www.codenameone.com/developer-guide.html">Codename One Developer Guide</a>.

Q: Is Codename One Free? Is it Open-Source?

Yes. Codename One is open-source and free for use commercially and non-commercially with no royalties or restrictions. You can use the free version to build anything you want without touching the cloud service and ship the results commercially. | Notice that the paid portions of Codename One aren't available in any competing cross platform product! Check out the <a href="https://www.codenameone.com/pricing.html">pricing page</a> for more details. | In the past it was harder to build without the cloud, this is no longer the case thanks to the <a href="https://www.codenameone.com/blog/moving-to-maven.html">Maven build</a>. Codename One is open-source you can download the code and use it. There is no licensing fee. There are no restrictions or strings attached. Even if you purchase the paid product there is no license that requires you to keep paying. Codename One provides free community support for everyone through <a href="https://stackoverflow.com/questions/tagged/codenameone">Stackoverflow</a> and the <a href="https://www.reddit.com/r/cn1/">Reddit</a> discussion forum. The paid portion is for higher grade support and for the cloud build system which requires servers (Macs, Windows machines etc.). We provide a free quota on their usage to prevent overuse which would deprive paying users from service. What are the limits of the free version? With the free version you are limited to 100 build credits per month. Notice you can increase the following limits by referring your friends or if you were r

Question 1

How to Get Started with Codename One?

Accepted Answer

The easiest and quickest way to get started with Codename One is to use the Codename One initializr.

Step 1 - Sign-up for a free Codename One account Step 2 - Generate a new project using Codename One initializr Step 3 - Develop and debug your app in your preferred IDE (IntelliJ/IDEA, Eclipse, VSCode or NetBeans) Step 4 - Create a build (Android, iOS, Windows, Mac, JavaScript, JavaSE etc)

| We recently moved to Maven so you might want to check out this article and use the Maven approach instead of the older one covered by most tutorials. Notice that a lot of the developer oriented material is still geared towards the plugins which is the older approach (and no longer needed).

If you prefer a video, check out this getting started tutorial:

${youtube}Getting Started

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Question 2

What's Codename One? How Does it Work?

Accepted Answer

Codename One is an open-source cross-platform Write Once Run Anywhere (WORA) framework to build native apps for iOS, Android, Desktop and Web with Java or Kotlin.

The core appeal is its unrestricted access to the native platform allowing developers to write native code directly from Java or Kotlin and access everything that the native mobile platform can provide. You can generates native OS binaries that you can upload to Apple/Google etc.

To understand how Codename One works, check the introduction or this stackoverflow answer.

| Notice that Codename One works with IntelliJ/IDEA, Eclipse, VSCode and NetBeans.

To understand Codename One's history, basics, features etc in detail, check Codename One Developer Guide.

Question 3

Is Codename One Free? Is it Open-Source?

Accepted Answer

Yes. Codename One is open-source and free for use commercially and non-commercially with no royalties or restrictions.

You can use the free version to build anything you want without touching the cloud service and ship the results commercially.

| Notice that the paid portions of Codename One aren't available in any competing cross platform product!

Check out the pricing page for more details.

| In the past it was harder to build without the cloud, this is no longer the case thanks to the Maven build.

Codename One is open-source you can download the code and use it. There is no licensing fee. There are no restrictions or strings attached. Even if you purchase the paid product there is no license that requires you to keep paying.

Codename One provides free community support for everyone through Stackoverflow and the Reddit discussion forum.

The paid portion is for higher grade support and for the cloud build system which requires servers (Macs, Windows machines etc.). We provide a free quota on their usage to prevent overuse which would deprive paying users from service.

What are the limits of the free version?

With the free version you are limited to 100 build credits per month. Notice you can increase the following limits by referring your friends or if you were r

Question 4

Can I use any JAR?

Accepted Answer

You can't use an arbitrary JAR "as is". Please also check the maven dependency discussion in this post.

You can wrap libraries as cn1libs but a library might use arbitrary Java code which might be a problem, see this.

We have a tutorial on porting native OS SDK's to Codename One in the developer guide.

There are a lot of 3rd party libraries adapted to Codename One and most of them are open source. e.g. this one enables camera preview. You can use that as a sample starting point.

Question 5

Porting an Android Project/Working with Android Studio

Accepted Answer

Check out this guide on porting an Android app to iOS with Codename One. Notice that you will need to redo a significant portion of the code.

We don't support Android Studio. Only IntelliJ/IDEA which is technically very similar only faster. Android Studio broke some functionality that we need in IntelliJ and offers no advantage for Codename One development. Since we don't support the Android API's outside of native code there is no need for that.

You can access Android "native" functionality (i.e. the full Android API) using native interfaces. See this video for an introduction to that concept.

Question 6

What's the JAR Size Limit?

Accepted Answer

| You can build an Uber or Facebook Clone and fit within the 1mb limit.

You can also increase the size limit by referring your friends.

The 1mb size applies to the JAR sent to the server, this is around 6kb for a barebones application. All of our demos and many 3rd party apps in the stores fall under this limit which is generally a good approach.

It doesn't limit the size of the final application or 3rd party libraries used which means you can still use a large library like Google Maps without hitting this limit. If you use a very heavy theme or many images (within the app JAR not downloaded dynamically) you will hit this limit.

There is a bit of an overview here on how to shrink the JAR overhead.

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