Question

以下代码不起作用： FileSystems.getDefault.getPath来自java.nio包

更新

方法createCalculation是：

注意：MyLocation是一个扩展MyMessage的案例类

def creatCalculation(myPlace: MyLocation): MyMessage = {
    if (some test) {
       //--- some code
    } else
       MyError("My Calculation already done")

        MyAck //returning the case object MyAck which is of type MyMessage
  }

// Req是来自：net.liftweb.http.Req

的类

val someVal: PartialFunction[Req, () => Box[LiftResponse]] {

case "create" :: Nil JsonPostAndApproval s =>
          postResponse(s, (j: JValue, p: Permissions, r: Req) => {
        createCalculation(fromJValue[MyLocation](j) = {
          case "MyAck" => {
             val myCalculator: Calculator = new Calculator(FileSystems.getDefault.getPath(fromJsonVal[MyLocation](s._1).path))
             val resultsMap = myCalculator.foreach( (p) => Map[String,  Int])
                 for( (myKey, myValue) <- resultsMap) {
                    printf("key: %s, value:  %s\n", myKey, myValue)
                 }
          }
        })
      } ) ("Failed to calculate")

 }

编译器抱怨如下：

[error] C:\Users\lulu\ExampleHandler.scala:129: missing arguments for
method fromJValue in package json;
[error] follow this method with `_' if you want to treat it as a partially applied function
[error]         createCalculation(fromJsonVal[MyLocation](j) = {
[error]                                  ^

这是fromJsonVal

的方法定义

/**
   * Routine to convert JValue to native type
   *
   * @param in JValue to convert
   * @tparam T native type to extract
   * @return extracted native type
   */
  def fromJsonVal[T: Manifest](in: JValue): T = in.extract[T]

JValue来自net.liftweb / json并且是：密封的抽象类JValue（）使用net.liftweb.json.Diff.Diffable扩展java.lang.Object { ＆LT;＆GT; }

更新：编译器在此代码行中报告错误

您认为我应该如何更正此编译错误？

   createCalculation(fromJValue[MyLocation](j) = {

Answer 1

如果没有完整的图片，我认为错误仅仅来自于您尝试将输出分配给方法和丢失的parens。没有完整的图片，我的猜测是你正在寻找更像的东西：

createCalculation(fromJValue[MyLocation](j)) match {
  case "MyAck"....

请注意j

之后的双重帮助

Scala：部分函数错误：如果要将其视为PartialFunction，请使用_

1 个答案: