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Scala 为什么';t HashMap.Map上的合并工作_Scala - Fatal编程技术网

Scala 为什么';t HashMap.Map上的合并工作

Scala 为什么';t HashMap.Map上的合并工作,scala,Scala,为什么HashMap.merged不能在Map上工作?例如: val resultMap = collection.immutable.HashMap[String, Int]() val justMap = collection.immutable.Map[String, Int]() resultMap.merged(justMap) 类型不匹配,请检查。改用++运算符: val firstMap = collection.immutable.HashMap[St

为什么HashMap.merged不能在Map上工作?例如:

    val resultMap = collection.immutable.HashMap[String, Int]()
    val justMap =  collection.immutable.Map[String, Int]()
    resultMap.merged(justMap)

类型不匹配,请检查。改用
++
运算符:

val firstMap = collection.immutable.HashMap[String, Int]()
val secondMap =  collection.immutable.Map[String, Int]()
val resultMap = firstMap ++ secondMap