CODEWITHSUNDEEP
kotlin
Dhruv Chadha
Dhruv Chadha

Reputation: 1177

Kotlin: Using method reference to a getter of another class

I have a class -

class ES {
    var issue: SomeClass? = null
}

I need to access its getter in another class -

class CSS {
   private val ref: Supplier<SomeClass?> = ES::issue
}

However this is not working. Its throws this error -

Type mismatch.
Required: Supplier<SomeClass?>
Found   : KMutableProperty1<ES, SomeClass?>

Can someone tell me what am I doing wrong? I am actually in the process of converting java code to kotlin.

UPDATE

I need a static reference to the getter of the ES class, similar to JAVA, where we can do ->

Function<ES, SomeClass> ref = ES::getIssue;

Upvotes: 0

Views: 399

Answers (1)

Tenfour04
Tenfour04

Reputation: 93629

In Kotlin, instead of using Supplier, you use functional syntax for the type. In this case, the equivalent of your Supplier<SomeClass?> would be () -> SomeClass? (assuming ES is an object since that's how you used it in your example code):

class CSS(/*...*/) {
   private val ref: () -> SomeClass? = ES::issue
}

But if you have to use Supplier specifically so it can be easily used with Java code, you can wrap your getter reference in a Supplier implementation:

class CSS(/*...*/) {
   private val ref: Supplier<SomeClass?> = Supplier(ES::issue)
}

Update If you want the getter without a specific instance of the class, similar to Function<ES, SomeClass> in Java, then you need to make ES a parameter of the function.

Either

private val ref: (ES) -> SomeClass? = ES::issue

or

private val ref: ES.() -> SomeClass? = ES::issue

I don't believe there's a way to do this with Supplier, but I don't think you could do it in Java with Supplier either.

Upvotes: 1

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