Question

我有一个Scala函数，它传递“Any”类型的消息。在大多数情况下，它将是一个大小为2的元组。接收此消息的函数需要查看元组元素的特定类型：

main() {
// call to function
// msg is of type Any.
    func (msg) 
}

现在在我的功能中，

function (msg : Any) {
    String inputType = msg.getClass.getCanonicalName
    if (inputType.compareTo("scala.Tuple2") == 0) {
        // I now know that the input to the function is a tuple..I want to extract the type of each element in this tuple.
        //something like:
        var tuple = msg.asInstanceof(scala.Tuple2) // This line gives an error. I want to cast object of Type Any to a tuple.
        var 1type = tuple._1.getClass.getCanonicalName
        var 2type = tuple._2.getClass.getCanonicalName
    }
}

Answer 1

为什么不使用pattern matching？

def function(msg: Any) = {
  msg match {
    case tuple @ (a: Any, b: Any) => tuple
  }
}

Answer 2

模式匹配

msg match {
   case (x,y) =>  ...
}

Answer 3

我在使用Scala Build Tools版本sbt-0.13.8

进行测试后得出了这个答案

def castfunction（msg：Any）：Tuple2 [Char，Int] = { msg match {case（x：Char，y：Int）=＆gt;元组2（x，y）} }

谢谢。弗兰克

向Tuple2投射任何东西

3 个答案: