To obtain a Java’s [Class](<https://docs.oracle.com/javase/8/docs/api/java/lang/Class.html>) object from Kotlin’s [KClass](<https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.reflect/-k-class/index.html>) use the .java extension property:

val stringKClass: KClass<String> = String::class
val c1: Class<String> = stringKClass.java

val c2: Class<MyClass> = MyClass::class.java

The latter example will be optimized by the compiler to not allocate an intermediate KClass instance.