1 package chapter08
 2 
 3 object Test03_MatchTupleExtend {
 4   def main(args: Array[String]): Unit = {
 5     // 1. 在变量声明时匹配
 6     val (x, y) = (10, "hello")
 7     println(s"x: $x, y: $y")
 8 
 9     val List(first, second, _*) = List(23, 15, 9, 78)
10     println(s"first: $first, second: $second")
11 
12     val fir :: sec :: rest = List(23, 15 , 9, 78)
13     println(s"first: $fir, second: $sec, rest: $rest")
14 
15     println("=====================")
16 
17     // 2. for推导式中进行模式匹配
18     val list: List[(String, Int)] = List(("a", 12), ("b", 35), ("c", 27), ("a", 13))
19 
20     // 2.1 原本的遍历方式
21     for (elem <- list){
22       println(elem._1 + " " + elem._2)
23     }
24 
25     // 2.2 将List的元素直接定义为元组，对变量赋值
26     for ((word, count) <- list ){
27       println(word + ": " + count)
28     }
29 
30     println("-----------------------")
31     // 2.3 可以不考虑某个位置的变量，只遍历key或者value
32     for ((word, _) <- list)
33       println(word)
34 
35     println("-----------------------")
36 
37     // 2.4 可以指定某个位置的值必须是多少
38     for (("a", count) <- list){
39       println(count)
40     }
41   }
42