Kotlin - 检查对象是否实现特定接口

Question

假设我有一些数据类，例如：

data class NameCreated(
    val index: Float,
    val name: String
) : ESEventPayload

然后我有一些方法，如果事件的类型<Event<out Any>>正在实现，我想返回 true ESEventPayload。

例如：

fun isItUsing(message: AcknowledgeableMessage<Event<out Any>>): Boolean =

I was hoping something like this would work, but it's not:

if (ESEventPayload::class.java.isAssignableFrom(message.body.payloadType::class.java)) {
   println("It's using the interface")
} else {
   println("It isn't using")
}

How do I go about doing this in Kotlin?

Any help would be appreciated.

Thanks.

Answer 1

使用is运算符，它看起来就像：

if (something is ESEventPayload) { ... }

这里没有理由使用isAssignableFrom. 事实上，它具有不智能铸造的负面后果。使用时is您可以...

if (something is ESEventPayload) {
   // something here is now smart cast as ESEventPayload, no casting needed
   println(something.eventPayloadMemberOrMethod) 
} 

请参阅： https: //kotlinlang.org/docs/reference/typecasts.html