Kotlin filter

役割:条件に合致した値のみリストに返却

使い方

filter

A.filter{ it XXXX }
→A(List)の1つ1つに対して順番に処理を実行し、XXXXの条件に合致するもののみリストに返却する

Stringのリストの各要素に対して処理実行

filter

  fun filter(){
    val okashiList = listOf("cookie","chocolate","pinapple","manjuu","chuppachapps")
    println(okashiList.filter { it.contains("c") })
  }

result

[cookie, chocolate, chuppachapps]

Integerのリストの各要素に対して処理実行

count

fun main(){
    val pieList = listOf("3","1","4","1","5","9","2","6","5","3","5","8","9","7","9","3","2","3","8")
    println(pieList.filter { it.toInt() % 2 == 0 })
    println(pieList.filter { it.toInt() % 2 != 0 })
}

result

[4, 2, 6, 8, 2, 8]
[3, 1, 1, 5, 9, 5, 3, 5, 9, 7, 9, 3, 3]