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为什么此代码在Scala 2.9.2中引发类型不匹配错误?我预计,getOrElse
返回类型为String
,但实际上它返回java.io.Serializable
:选项getOrElse类型不匹配错误
scala> implicit def StringToOption(s:String) = Option(s)
StringToOption: (s: String)Option[String]
scala> "a".getOrElse("")
res0: String = a
scala> var opt:Option[String] = "a".getOrElse("")
<console>:8: error: type mismatch;
found : java.io.Serializable
required: Option[String]
var opt:Option[String] = "a".getOrElse("")
^
这是OK:
scala> implicit def StringToOption(s:String): Option[String] = Option(s)
StringToOption: (s: String)Option[String]
scala> var b:Option[String] = "a".getOrElse("") toString
b: Option[String] = Some(a)
> sschaef感谢修复我的英语! – sndyuk