CODEWITHSUNDEEP
springintellij-ideakotlin
Gustavo Passini
Gustavo Passini

Reputation: 2678

IntelliJ can't find Spring bean from Kotlin object

I have a Spring Boot 2 + Kotlin application opened with IntelliJ 2019.1.

In this application I annotate some Kotlin objects with @Component. Example:

@Component
object MyObject: MyInterface {
    // code
}

I have many different implementation of MyInterface (all with Kotlin objects) and I want to inject all of them in a list in another bean. Example:

@Component
class MyComponent @Autowired constructor(private val objects: List<MyInterface>) {
    // code
}

The code runs correctly (the beans are inject in the list objects) but IntelliJ shows an error saying:

Could not autowire. No beans of '? extends MyInterface' or 'List<? extends MyInterface>' types found.

If I change 'object' to 'class' at 'MyObject', the error disappears.

My questions are:

Upvotes: 2

Views: 4083

Answers (3)

Sergei Rybalkin
Sergei Rybalkin

Reputation: 3453

I would recommend not to use kotlin objects with @Component or any other bean annotation.

There are two aspects and heaving a mix of them leads to lots of problems:

  1. It might be several ApplicationContext instances in your application.
  2. Kotlin object is related to a specific ClassLoader

Upvotes: 2

Gustavo Passini
Gustavo Passini

Reputation: 2678

For information, as a possible workaround while the ticket created by Николай in this answer is not treated, I'm ignoring the error/warning only where I need with @Suppress("SpringJavaInjectionPointsAutowiringInspection"). Example:

@Suppress("SpringJavaInjectionPointsAutowiringInspection")
@Autowired
private lateinit var kotlinObjectBeans: List<MyInterface>

I hope it can help others that don't want to disable this check elsewhere.

Upvotes: 2

Николай Митропольский
Николай Митропольский

Reputation: 917

It is a little bit strange to use Kotlin objects as @Component-s, because if your class knows that it will be used inside Spring-container you'll get more flexibility if you delegate to Spring the decision should this class be a singleton or not and all the other lifecycle management.

But practically I don't see any reason why it could be "not recommended" if you know what you are doing, and aware of probably bugs if your object become stateful.

So I think IDEA should support your case, and I've filled up a ticket IDEA-211826

Upvotes: 1

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