how to use spring annotations like @Autowired or @Value in kotlin for primitive types?

Question

Autowiring a non-primitive with spring annotations like

@Autowired lateinit var metaDataService: MetaDataService 

works.

But this doesn't work:

@Value("\${cacheTimeSeconds}") lateinit var cacheTimeSeconds: Int 

with an error:

lateinit modifier is not allowed for primitive types.

How to autowire primitve properties into kotlin classes?

Answer 1

You can also use the @Value annotation within the constructor:

class Test(     @Value("\${my.value}")     private val myValue: Long ) {         //...   } 

This has the benefit that your variable is final and none-nullable. I also prefer constructor injection. It can make testing easier.

Answer 2

@Value("\${cacheTimeSeconds}") lateinit var cacheTimeSeconds: Int

should be

@Value("\${cacheTimeSeconds}") val cacheTimeSeconds: Int? = null