--- lang: ja-jp breaks: true --- # Kotlin ビックリマーク二つ`!!`(Not-Null Assertion Operator) の意味 2021-08-06 ## C#の`.Value`と同じ意味 > Not-Null Assertion Operator > https://engawapg.net/kotlin/116/ ```kotlin= val str: String? = "test" val len = str!!.length // 4 ``` ```kotlin= val str: String? = null val len = str!!.length // NullPointerException ``` ###### tags: `Kotlin` `!!` `Not-Null Assertion Operator`