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javakotlinkotlin-interop

kotlin - non null mark for platform types / methods

I often use UUID.randomUUID(). Type inferred by kotlin is UUID!. is there any way to tell kotlin that return type of this specific method is UUID and is always non null? or do i have to do everywhere UUID.randomUUID()!! or implement my own method?

Solution

  • If you explicitly declare the types, it should declare them non-nullable instead of as a platform type.

    val id1 = UUID.randomUUID() // UUID!
val id2: UUID = UUID.randomUUID()  // UUID

    I do this with a function to make things a bit easier. By declaring the return type, it has the same effect:

    fun generateUUID(): UUID = UUID.randomUUID()

    Or as an extension:

    fun UUID.next(): UUID = UUID.randomUUID()