「Kotlin」isEmptyメソッドでmapが空であるかを判定する
環境
Windows11 pro 64bit
Java 17.0.2
kotlin 1.6.10
書式
map名.isEmpty()
isEmpty関数を使って、mutamutableMapでmapが空であるかを判定します。
使用例
fun main() {
val cftA = mutableMapOf('s' to 22, 't' to 33)
val cftB: Map<Char, Int> = mutableMapOf()
val cftC: Map<Char?, Int?> = mutableMapOf(null to null)
println( cftA.isEmpty() )
println( cftB.isEmpty() )
println( cftC.isEmpty() )
}
fun main() {
val cftA = mutableMapOf('s' to 22, 't' to 33)
val cftB: Map<Char, Int> = mutableMapOf()
val cftC: Map<Char?, Int?> = mutableMapOf(null to null)
println( cftA.isEmpty() )
println( cftB.isEmpty() )
println( cftC.isEmpty() )
}
fun main() {
val cftA = mutableMapOf('s' to 22, 't' to 33)
val cftB: Map<Char, Int> = mutableMapOf()
val cftC: Map<Char?, Int?> = mutableMapOf(null to null)
println( cftA.isEmpty() )
println( cftB.isEmpty() )
println( cftC.isEmpty() )
}
実行結果
false
true
false