Mavzu: Android ilovalarini ishlab chiqishda Kotlin dasturlash tilidan foydalanish

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Bog'liq
mus ish mobil

oxirgi / oxirgiOrNull

Last () funktsiyasi oxirgi elementni oqimdan chiqaradi, faqat funktsiyadan farqli o'laroq first()(hech bo'lmaganda Kotlin 1.5.1 versiyasi uchun) u shartni qabul qilmaydi: u ham shartni qabul qilishi mumkin:

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2018-05-01 xoxlasa buladi 121 2
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sakkiz

import kotlinx.coroutines.flow.*
suspend fun main(){
val userFlow = listOf("Tom", "Bob", "Alice", "Sam").asFlow()
val lastUser = userFlow.last()
println("Last User: $lastUser") // Last User: Sam
}

Agar oqim bo'sh bo'lishi ehtimoli bo'lsa, siz elementlar bo'lmasa qaytariladigan lastOrNull funktsiyasidan foydalanishingiz mumkin null:

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import kotlinx.coroutines.flow.*
suspend fun main(){
val userFlow = listOf("Tom", "Bob", "Alice", "Sam").asFlow()
val lastUser = userFlow.lastOrNull()
if(lastUser!=null) println("Last User: $lastUser")
}

yagona / singleOrNull

Agar oqim faqat bitta elementni o'z ichiga olgan bo'lsa, yagona () funksiyasi oqimning bitta elementini qaytaradi . Agar oqimda hech qanday element bo'lmasa, istisno tashlanadi va oqimda bir nechta element bo'lsa, istisno tashlanadi .NoSuchElementExceptionIllegalStateException

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to'qqiz
o'n
o'n bir

import kotlinx.coroutines.flow.*
suspend fun main(){
val userFlow = listOf("Tom").asFlow()
try {
val singleUser = userFlow.single()
println("Single User: $singleUser")
}
catch(e:Exception) { println(e.message) }
}

Shu bilan bir qatorda,

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