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

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.

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

should be

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

I just used Number instead of Int like so...

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

The other options are to do what others mentioned before...

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

Or you can simply provide a default value like...

    @Value("\${cacheTimeSeconds}")
    var cacheTimeSeconds: Int = 1

In my case I had to get a property that was a Boolean type which is primitive in Kotlin, so my code looks like this...

    @Value("\${myBoolProperty}")
    var myBoolProperty: Boolean = false

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