转换时异常

src/senior/Exception/RainException.kt

@@ -4,6 +4,8 @@ class RainException(override val message: String?) : Throwable() {
 }
 
 fun main(args: Array<String>) {
-    var name: String? = null
+    var name: String? = "null"
     name?.length ?: throw RainException("rain自定义异常")
+
+    println("name.length = ${name.length}")
 }