Guys, how can I resolve this problem? What I need to import? > Unresolved reference: WeakReferenc...

# multiplatform

[Dmitry Motyl]

Guys, how can I resolve this problem? What I need to import?

Unresolved reference: WeakReference

[diesieben07]

WeakReference is a class from JDK, it can only be used in Java modules.

[svyatoslav.scherbina]

Kotlin/Native has WeakReference too: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.native.ref/index.html

[Dmitry Motyl]

Which module is it needed to import ?

[ribesg]

You should provide more details about what you’re doing. Where did you put that reference that is unresolved?

[ribesg]

If you’re in common sourceSet and only have jvm/android and native/ios targets, you can just use expect class WeakReference<T: Any> somewhere in your common code I guess

[Dmitry Motyl]

In commonMain module

[ribesg]

I you have a js target you can’t use WeakReference

[Dmitry Motyl]

Ok. Thx. I got it

[Dmitry Motyl]

Why WeakReference has method clear?
I thought it must work automatically

[ribesg]

Weak reference doesn’t mean no reference

[Dmitry Motyl]

I must call clear directly?

[diesieben07]

No.

[Dmitry Motyl]

If I use expect class WeakReference<T: Any> I get issue that It has no actual declaration in module iosMain for Native =(

[ribesg]

You need a typealias

[ribesg]

actual typealias WeakReference<T> = kotlin.native.ref.WeakReference<T>

[ribesg]

And on the JVM side actual typealias WeakReference<T> = java.lang.ref.WeakReference<T>

[ribesg]

You probably need to add things like a get function etc

[Dmitry Motyl]

hmm, strange
I think It must be simpler

[Dmitry Motyl]

Does somebody know example of using WeakReference in common module ?

[ribesg]

What’s so hard?

[ribesg]

// Common
expect class WeakReference<T: Any> {
    fun get(): T?
}

// JVM/Android
actual typealias WeakReference<T> = java.lang.ref.WeakReference<T>

// Native/iOS
actual typealias WeakReference<T> = kotlin.native.ref.WeakReference<T>