内联时的 Kotlin 空指针异常，但分离时不会

Question

When collapsing code down into a single line, a null pointer exception starts getting thrown. But if separated into multiple variables, then it works just fine. Noticed the issue when upgrading to kotlin 1.5.0 on android api 31.

Code inline:

embeddedBasket?.basket?.items?.items?.asSequence()?.map { it.productItem }?.toMutableList() ?: mutableListOf() // throws null pointer exception

Code separated:

val productResponses = embeddedBasket?.basket?.items?.items // null
val asSequence = productResponses?.asSequence() // null
val map = asSequence?.map { it.productItem } // null
val toMutableList = map?.toMutableList() // null
val endList = toMutableList ?: mutableListOf() // Empty MutableList

Any idea why?

Edit:

Found the cause of the issue. It was Gson producing null values when converting from json elsewhere in the codebase. Gson and Kotlin issue

Answer 1

Found the cause of the issue. It was Gson producing null values when converting from json elsewhere in the codebase. Gson and Kotlin issue