kotlin-stdlib/kotlin.collections/AbstractMutableCollection/add

add

expect abstract override fun add(element: E): Boolean(source)

Adds the specified element to the collection.

Since Kotlin

1.3

Return

true if the element has been added, false if the collection does not support duplicates and the element is already contained in the collection.

Samples

import kotlin.math.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   val list = mutableListOf('a', 'b', 'c')
println("list.add('c') is ${list.add('c')}") // true
println(list) // [a, b, c, c] 
   //sampleEnd
}
import kotlin.math.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   val set = mutableSetOf('a', 'b', 'c')
// Sets do not support duplicates, so there is no way to add yet another 'c'
println("set.add('c') is ${set.add('c')}") // false
println(set) // [a, b, c] 
   //sampleEnd
}
actual abstract override fun add(element: E): Boolean(source)

Adds the specified element to the collection.

Since Kotlin

1.1

Return

true if the element has been added, false if the collection does not support duplicates and the element is already contained in the collection.

Samples

import kotlin.math.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   val list = mutableListOf('a', 'b', 'c')
println("list.add('c') is ${list.add('c')}") // true
println(list) // [a, b, c, c] 
   //sampleEnd
}
import kotlin.math.*
import kotlin.test.*

fun main() { 
   //sampleStart 
   val set = mutableSetOf('a', 'b', 'c')
// Sets do not support duplicates, so there is no way to add yet another 'c'
println("set.add('c') is ${set.add('c')}") // false
println(set) // [a, b, c] 
   //sampleEnd
}
actual abstract override fun add(element: E): Boolean(source)

Adds the specified element to the collection.

This method is redeclared as abstract, because it's not implemented in the base class, so it must be always overridden in the concrete mutable collection implementation.

Since Kotlin

1.1

Return

true if the element has been added, false if the collection does not support duplicates and the element is already contained in the collection.