CODEWITHSUNDEEP
androidkotlingenericskotlin-android-extensions
Masksway
Masksway

Reputation: 225

How to use Generics in Kotlin extension function

I had 2 functions that does basically the same thing, so I thought to create an extension function.

The problem is that I need to extract the data of each class in order to get the correct result, I thought of creating a Generic function, and inside this function decide which class member to access inside when statement.

But when I try to call T inside the when statement, I'm getting Type parameter 'T' is not an expression

What am I doing wrong?

My function:

fun <T: Any> List<T>.extractWithSepreation(errorString: String): String {
    var errorString = "There is no available $errorString"

    if (this.isEmpty()) {
        return errorString
    }
    
    errorString = ""
    this.forEachIndexed { index, item ->
        when(T)
    }

}

Upvotes: 1

Views: 858

Answers (1)

Bartek Lipinski
Bartek Lipinski

Reputation: 31438

The error message pretty much says it all. T is not an expression, so it cannot be used inside when(...). T just refers to the class of the item of the List.

Didn't you mean using something like:

when(item) {
   is ClassA -> doSomething()
   is ClassB -> doSomethingElse()
}

?

Upvotes: 3

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