Error while writing Kotlin extension function

Question

Below is my extension:

fun String?.toDoubleOrDefault(): Double = this?.toDoubleOrNull() ?: 0.0

when I try to apply it like this:

var a:String? = "1000"
var b:String? = "2000"
var c = a?.toDoubleOrDefault()*b?.toDoubleOrDefault()

I get this error: Type mismatch.

Required:Double

Found:Double?

Could anyone please explain what I am Doing wrong?

Do a.toDoubleOrDefault()*b.toDoubleOrDefault(). No need for null check since you already do so in the method. This is also the reason why you're getting Double? as a return value from that call. — Beko
– Beko, Commented Aug 8, 2020 at 9:41
as a side note the extension function would be more flexible as : fun String?.toDoubleOrDefault(defaultVal : Double = 0.0): Double = this?.toDoubleOrNull() ?: defaultVal — Mark
– Mark, Commented Aug 8, 2020 at 9:52

Shalu T D · Accepted Answer · 2020-08-08 09:48:57Z

1

Please try below code:

    var a:String? = "1000"
    var b:String? = "2000"
    var c  = a.toDoubleOrDefault()*b.toDoubleOrDefault()

answered Aug 8, 2020 at 9:48

Shalu T D

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