斯卡拉地图不迭代到所有元素

Question

我想在Scala文件中搜索给定状态树的列表。

下面是示例文件（制表符分隔）： -

Quercus acerifolia mapleleaf oak MN 
Quercus _acutidens  CA 
Quercus acutissima sawtooth oak AL,GA,LA,MD,MS,NC,PA,VA 
Quercus agrifolia California live oak CA 
Quercus alba white oak AL,AR,CT,DC,DE,FL,GA,IA,IL,IN,KS,KY,LA 
Quercus ajdfensis Ajo Mountain scrub oak ,MN 

我的代码： -

//declaring package 
package HW10 

//declaring object 
object TreesStub { 

//importing Source package for files import 
    import scala.io.Source 

    //assigning the file path to filename variable 
    val fileName = "trees.tsv" 

    //defining Main function 
    def main(args: Array[String]): Unit = { 

    //reading source file from a file which is tabe separated 
    val treeList: List[String] = Source.fromFile(fileName).getLines.toList 

    //calling searchTrees method for a given State 
    searchTrees("MN", treeList) 

    //searchTrees method logic for a given State and print it 
    def searchTrees(state: String, trees: List[String]): Unit = { 

     //defining mutable empty map collection as "states" 
     var states = collection.mutable.Map[String, String]() 

     //Searching the tree list for a given state and adding the map and //tree list to the states map collection 

    trees.map(x => (x.split("\t", -1))).filter((_.length > 2)).map(x => 

     //using try catch block for handling match not found exception 
     try { 
     if (x(2).contains(state)) states += (state -> x(0)) 
     } 
     catch { 
     //exception if caught to None 
     case e: Exception => println(s"None") 
     }) 
     //printing map "states" values 
     states.foreach(println) 
    } 
    } 
} 

输出我得到如下： - (MN,Quercus acerifolia)

预期输出： - （州名，树名单）

(MN,Quercus acerifolia) 
(MN,Quercus ajdfensis) 

我只能打印一个不能打印所有比赛的比赛。不知道代码中出了什么问题？看起来地图只迭代一次而不是所有的匹配。请让我知道如何打印所有比赛？

Answer 1

states是一张地图，一个数据结构，它将每个键映射到一个单个值。因此，如果要为同一个键累积多个结果，则映射是错误的数据结构。

Answer 2

Quercus acerifolia mapleleaf oak MN 
Quercus _acutidens  CA 
Quercus acutissima sawtooth oak AL,GA,LA,MD,MS,NC,PA,VA 
Quercus agrifolia California live oak CA 
Quercus alba white oak AL,AR,CT,DC,DE,FL,GA,IA,IL,IN,KS,KY,LA 
Quercus ajdfensis Ajo Mountain scrub oak ,MN 

您是否试过寻找MN以外的东西？ 您的最后一行是,MN，这可能与您的字符串比较有关。