Kotlin 获取字符串类型

我找不到如何使用 Kotlin 语言获得 String这样的变量(或常量)类型，比如 typeof(variable)。如何做到这一点？

java
kotlin

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小开

if (obj is String) {
print(obj.length)
}


if (obj !is String) { // same as !(obj is String)
print("Not a String")
}

小开

最佳答案

You can use one of the methods that best suits your needs:

val obj: Double = 5.0


System.out.println(obj.javaClass.name)                 // double
System.out.println(obj.javaClass.kotlin)               // class kotlin.Double
System.out.println(obj.javaClass.kotlin.qualifiedName) // kotlin.Double

You can fiddle with this here.

小开

There is a simpler way using simpleName property and avoiding Kotlin prefix.

val lis = listOf(1,2,3)

lis is from type ArrayList. So one can use

println(lis.javaClass.kotlin.simpleName)  // ArrayList

or, more elegantly:

println(lis::class.simpleName)  // ArrayList

小开

You can use the '::class' keyword that gives the type of an instance. The property .simpleName return the string name of the returned class.

var variable = MyClass()


var nameOfClass = variable::class.simpleName


nameofClass >> "MyClass"