Good morning, everyone. I’m having trouble with K...

# getting-started

[df]

Good morning, everyone.

I’m having trouble with Kotlin’s type system while extending an existing Java class. Could someone take a look at the following gist and help me out?

[Joshua Hansen]

Try replacing Any with Any? in the class header? Just a guess.

[Joshua Hansen]

Just looking at the difference between the java code and kotlin code, Object is the same as Any?, not Any

[df]

Do you mean the first argument to the ctor or the type of the first generic?

[df]

But I get the same result with the following implementation

class MapEqualJsonBinaryType : MutableDynamicParameterizedType<Any?, JsonBinaryJdbcTypeDescriptor, JsonJavaTypeDescriptor> {
    constructor() : super(
        Any::class.java as Class<Any?>,
        JsonBinaryJdbcTypeDescriptor.INSTANCE,
        MapEqualJsonJavaTypeDescriptor(JsonConfiguration.INSTANCE.objectMapperWrapper)
    )

    constructor(objectMapperWrapper: ObjectMapperWrapper) : super(
        Any::class.java as Class<Any?>,
        JsonBinaryJdbcTypeDescriptor.INSTANCE,
        MapEqualJsonJavaTypeDescriptor(objectMapperWrapper)
    )
}

[df]

Anyone? 🙂

[Arne Jans]

It is difficult to see the problem without a minimal project with relevant dependencies and participating code-files.
Your error-message in the gist-comment suggests that the forEachJdbcType-param action should be declared as nullable somewhere in a derived class, I think maybe the Java-code marks it as @Nullable and the kotlin-compiler tries to honor that (since it explains it needs the param-type IndexedConsumer<*>?).

[Arne Jans]

You should be able to let IntelliJ (if you are using that) suggest a quickfix by generating a fitting method-override in the kotlin class.
Or you could try to make the param @Nullable in the default implementation.

[df]

Hey Arne, I just pushed a minimum failing project to github: https://github.com/rebuy-de/kotlin-type-system

[Wout Werkman]

It smells like a compiler bug to me, because the code works in Kotlin 2.1.0 when I tested it

[df]

Oh, interesting

[df]

Unfortunately we won't move to Kotlin 2.x before Spring Framework 7 is shipped

[df]

Justed verified that it compiles with Kotlin 2.1.0, yet IntellIJ shows an error

[df]

image.png

[Wout Werkman]

Perhaps your IntelliJ is still in K1 mode

[df]

not sure what else could be changed

[Wout Werkman]

Try finding the K2 setting. It's a checkbox somewhere in the settings. Should be conveniently findable via search in settings.