CODEWITHSUNDEEP
kotlinintellij-idea
Raphael
Raphael

Reputation: 1730

HelloWorld in Kotlin gives error "Could not find or load main class"

I spent the last 1,5 hour trying to make this simple tutorial work in IntelliJ IDEA, as you can see in this video.

When trying to run the code, I get the error:

/[...] -Dfile.encoding=UTF-8 src.HelloKt
Error: Could not find or load main class src.HelloKt
Caused by: java.lang.ClassNotFoundException: src.HelloKt

I have tried setting up SDK, invalidating cache, removing .idea and .gradle, rebuilding project, deleting the profile and adding it again. I tried those actions in different orders.

Here's a screenshot of the project: enter image description here

It also complains Kotlin is not configured, but I have already configured it.

Here's the run configuration: enter image description here

Here are the project settings: enter image description here

Upvotes: 3

Views: 3705

Answers (1)

Sam
Sam

Reputation: 9954

Your Hello.kt file needs to be somewhere inside the src/main folder, probably in src/main/kotlin. This is different from the tutorial, because your project is using Gradle, and the one in the tutorial isn't. I think this is because newer versions of IntelliJ use Gradle by default for new projects, which wasn't the case when the tutorial was written.

The use of src/main/kotlin and src/test/kotlin as source code directories is a convention in Gradle (and Maven). When importing a Gradle project into IntelliJ, main becomes a module, and kotlin becomes a source folder within that module. The same goes for test. In your screenshots, the bold text and blue icons on main and test confirm that's how your project is set up. Files outside of those folders aren't treated as source files, which explains why your Hello.kt file isn't being compiled or recognised correctly.

It's likely that the default behaviour of IntelliJ when creating a new project has changed since this tutorial was written. In the tutorial, they select "Kotlin" as the project type and this creates a project that doesn't use Gradle. As a result, the project doesn't use the src/main/kotlin directory structure.

I can see from your video that you selected the same option, but on the next screen, IntelliJ still automatically selected Gradle as the build system for the new project. To match the project structure used in the tutorial, I think you would need to select "IntelliJ" as the build system.

Upvotes: 4

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