Question 1

Where do I Start?

Accepted Answer

Check out this post covering tutorials, documentation and resources available to developers https://www.codenameone.com/blog/tutorials-resources-learn-java-mobile-videos-courses-ios-android.html

We're currently in the midst of moving 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.

You can get online help via stackoverflow: http://stackoverflow.com/tags/codenameone

Or in the discussion forum: https://www.codenameone.com/discussion-forum.html

If you experience problems you can leave your email in the chat widget and we'll try to help.

Question 2

What's Codename One? / How does it Work?

Accepted Answer

Codename One is a tool for software developers that lets us write mobile apps using Java or Kotlin. It generates native OS binaries that you can upload to Apple/Google etc. To understand the basics of Codename One check out the 3 minute videos in the download section https://www.codenameone.com/download.html

${youtube}Hello Codename One (NetBeans Edition)

Notice that Codename One works with Eclipse, IntelliJ/IDEA and NetBeans…

To understand how Codename One works, its history etc. check our developer guide here which gives a birds eye view in the first chapter: https://www.codenameone.com/manual/

you can also check out this stackoverflow answer: http://stackoverflow.com/questions/10639766/how-codename-one-works/10646336

You can also check out this video where we give the long form explanation of what is Codename One:

${youtube}What is Codename One

For more about Codename One check out this post covering the extensive set of tutorials/docs/videos: https://www.codenameone.com/blog/tutorials-resources-learn-java-mobile-videos-courses-ios-android.html

The core advantages of Codename One are:

Write Once Run Anywhere support with no special hardware requirements and 100% code reuse
Compiles Java/Kotlin into native code for iOS, UWP (Universal Windows Platform), Android and even JavaScript/PWA
Open Source and Free with commercial backing/support
Easy to use with 100% portable Drag and Drop GUI builder
Full access to underlying

Question 3

Is Codename One Free?

Accepted Answer

Codename One has a free version and paid versions. So yes. Notice that the paid portions of Codename One aren't available for free in any competing cross platform product!

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 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.

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 referred by a friend. See this article for details. 1 credit == 1 build Except for iOS where 8 credits == 1 build to offset the higher costs of Mac servers. Other than that there is a JAR size limit of 1mb. Notice that this is a very high limit as it applies only to your bytecode and not to Codename One code and you can create pretty remarkable apps within this limit. E.g. our Uber clone and Facebook clone apps are well below that limit.

Just so we are 100% clear: you are allowed to use your generated apps commercial

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: https://www.codenameone.com/cn1libs.html but a library might use arbitrary Java code which might be a problem see https://www.codenameone.com/blog/why-we-dont-support-the-full-java-api.html

We have a tutorial on porting native OS SDK's to Codename One in the developer guide and in video form https://www.codenameone.com/blog/integrating-3rd-party-native-sdks-part-1.html

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 https://github.com/codenameone/CameraKitCodenameOne You can use that as a sample starting point.

Question 5

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 https://www.codenameone.com/blog/shrinking-sizes-optimizing.html

Question 6

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 https://www.codenameone.com/blog/port-native-android-app-ios-iphone-guide.html

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: https://www.codenameone.com/how-do-i---access-native-device-functionality-invoke-native-interfaces.html

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