none

fun <T> Sequence<T>.none(): Boolean(source)

Returns true if the sequence has no elements.

The operation is terminal.

Since Kotlin

1.0

Samples

import kotlin.test.*

fun main() { 
   //sampleStart 
   val emptyList = emptyList<Int>()
println("emptyList.none() is ${emptyList.none()}") // true

val nonEmptyList = listOf("one", "two", "three")
println("nonEmptyList.none() is ${nonEmptyList.none()}") // false 
   //sampleEnd
}
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val emptyList = emptyList<Int>()
println("emptyList.none() is ${emptyList.none()}") // true
val nonEmptyList = listOf("one", "two", "three")
println("nonEmptyList.none() is ${nonEmptyList.none()}") // false 
Open in Playground →
Target: JVMRunning on v.2.1.20

inline fun <T> Sequence<T>.none(predicate: (T) -> Boolean): Boolean(source)

Returns true if no elements match the given predicate.

The operation is terminal.

Since Kotlin

1.0

Samples

import kotlin.test.*

fun main() { 
   //sampleStart 
   val isEven: (Int) -> Boolean = { it % 2 == 0 }
val zeroToTen = 0..10
println("zeroToTen.none { isEven(it) } is ${zeroToTen.none { isEven(it) }}") // false
println("zeroToTen.none(isEven) is ${zeroToTen.none(isEven)}") // false

val odds = zeroToTen.map { it * 2 + 1 }
println("odds.none { isEven(it) } is ${odds.none { isEven(it) }}") // true

val emptyList = emptyList<Int>()
println("emptyList.none { true } is ${emptyList.none { true }}") // true 
   //sampleEnd
}
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val isEven: (Int) -> Boolean = { it % 2 == 0 }
val zeroToTen = 0..10
println("zeroToTen.none { isEven(it) } is ${zeroToTen.none { isEven(it) }}") // false
println("zeroToTen.none(isEven) is ${zeroToTen.none(isEven)}") // false
val odds = zeroToTen.map { it * 2 + 1 }
println("odds.none { isEven(it) } is ${odds.none { isEven(it) }}") // true
val emptyList = emptyList<Int>()
println("emptyList.none { true } is ${emptyList.none { true }}") // true 
Open in Playground →
Target: JVMRunning on v.2.1.20

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