Kotlin - 针对 HashMap 的对象类型检查显示警告

Question

我正在检查 Serializable在将其转换为 HashMap<String, String> 之前键入.但它给出了以下警告；

Cannot check for instance of erased type: kotlin.collections.HashMap /* = java.util.HashMap */

有没有办法检查是否 Serializable是 HashMap<String, String> 的类型那么安全施法吗？

params = if (it.getSerializable(ARG_PARAMS) is HashMap<String, String>) {
             it.getSerializable(ARG_PARAMS) as HashMap<String, String>
         } else null

Answer 1

实际上，您无法检查对象是否具有类型 HashMap<String, String>因为类型参数在运行时会被删除。我想建议你只使用一个安全的 Actor :

params = arguments?.getSerializable(ARG_PARAMS) as? HashMap<String, String>

Important:

It might be not clear but my code doesn't check that argument really has type HashMap<String, String>. You can pass HashMap<String, Int> and in some case, you'll get an error. In my snippet you just say to the compiler: "I know that there will be HashMap<String, String>. Just give it to me". params will be null only when there is no argument or its type differs from HashMap.