Scala For循环和元组树集的类型不匹配错误

我是一名新的Scala程序员，遇到了一个问题。我正在编写一个函数来获取的数目。当我试图从for循环（在If/Else语句中封装的底部附近）获取值时，它会给我一个类型不匹配错误。我期待一个带有字符串和Int（scala.collection.mutable.TreeSet[（String，Int）]）的树集元组，但它说它返回一个单位

以下是我的说明，我相信如果我解决了这个错误，它应该会起作用

注意：返回类型是元组的树集 其类型为（String，Int）。例如，给定人员列表（“tom”， “安”、“罗伯”、“罗伯”、“安”、“汤姆”、“帕特”、“罗伯”、“帕特”、“汤姆”）您的功能应该是 返回树集（（汤姆，3），（罗布，3））。注意：最大的骗子有一条领带， 您必须返回集合中所有最大的骗子。仅显示姓名的列表 一次返回一个空树集。“

***函数“crooks”和“a”在未显示的其他位置均有定义

  def biggestCrooks(people: List[String]): TreeSet[(String,Int)] = {

    val crooksListed = crooks(people).toList //Runs my one function that gives me the
                                         // list of criminals with more than one offense

    var numCounted = new Array[Int](crooksListed.size) // Array to hold the number of times a person name 
                                                       //appears

    for(nameIndex <- 0 until crooksListed.size){ // Counts the number of times a name appears
      val counter = people.count(_.equals(crooksListed(nameIndex))) //Stores that name in the array
      numCounted(nameIndex) = counter //Stores the num in the index associated with the name

     }
    var largestValue = numCounted.max // Largest value in the array
    val numValues = numCounted.count(_ == largestValue) // Number of times the value appears
    var indeces : Set[Int] = Set()
    var completeList : TreeSet[(String, Int)] = TreeSet() // Completed list of all names / values

    if(numValues > 1){// Used JIC there are multiple instances of numValues
    for(i <- 0 until numCounted.length){ //If there are multiple instances, find the indeces of them
      if(numCounted(i) == largestValue)
        indeces(i)                       //add the index to the array
    }
    val wow = indeces.toList //Converts a mutable Set to an immutable list
     for(i <- 0 until wow.size){ //iterate through the indeces and associate with names
       completeList.map(crooksListed(wow(i)), wow(i)) //Maps the values to the completeList TreeSet
       //Supposed to solve problem with mismatched types

     } 
    }
    else{

      completeList.map(i => (crooksListed(numCounted.indexOf(largestValue)), largestValue)) //Maps the values to the TreeSet
    }
  }// end biggestCrook

println(biggestCrooks(a))

def biggestCrooks（人物：List[String]）：TreeSet[（String，Int）]={
val crooksListed=crooks（people）.toList//运行我的一个函数，该函数为我提供
//一次以上犯罪的罪犯名单
var numCounted=new Array[Int]（crokslisted.size）//保存人名次数的数组
//出现
对于（nameIndex 1）{//使用的JIC，有多个numValue实例
对于（i请记住，scala中的每个语句都是一个表达式，每个表达式都有一个返回类型，应该返回一些内容。在示例if-else语句的第一个分支中，返回nothing，在scala中，它表示单位类型：

if（numValues>1）{//Used JIC有多个numValues实例
为了
if(numValues > 1){// Used JIC there are multiple instances of numValues
  for(i <- 0 until numCounted.length){ //If there are multiple instances, find the indeces of them
    if(numCounted(i) == largestValue)
      indeces(i)                       //add the index to the array
  }
  val wow = indeces.toList //Converts a mutable Set to an immutable list
  for(i <- 0 until wow.size){ //iterate through the indeces and associate with names
    completeList.map(crooksListed(wow(i)), wow(i)) //Maps the values to the completeList TreeSet
    //Supposed to solve problem with mismatched types

  }
// this for loop returns Unit, it just iterates on elements, and you need to add return value for compile
}
else{

  completeList.map(i => (crooksListed(numCounted.indexOf(largestValue)), largestValue)) //Maps the values to the TreeSet
// in this place you return mapped cimpleteList as Tree, but be carefull it's empty
}

if (numValues > 1) { // Used JIC there are multiple instances of numValues
  for (i <- numCounted.indices) { //If there are multiple instances, find the indeces of them
    if (numCounted(i) == largestValue)
      indeces(i) //add the index to the array
  }
  indeces.map(w => crooksListed(w) -> w).foldLeft(TreeSet.empty[(String, Int)]){
    case (tree, pair) => tree + pair
  }
} else {
  completeList.map(i => (crooksListed(numCounted.indexOf(largestValue)), largestValue)) //Maps the values to the TreeSet
}