Scala mutable.Map可变的Map

 1 package chapter07
 2
 3 import scala.collection.mutable
 4
 5 object Test09_MutableMap {
 6   def main(args: Array[String]): Unit = {
 7     // 1. 创建map
 8     val map1: mutable.Map[String, Int] = mutable.Map("a" -> 13, "b" -> 25, "hello" -> 3)
 9     println(map1)
10     println(map1.getClass)
11
12     println("==========================")
13
14     // 2. 添加元素
15     map1.put("c", 5)
16     map1.put("d", 9)
17     println(map1)
18
19     map1 += (("e", 7))
20     println(map1)
21
22     println("====================")
23
24     // 3. 删除元素
25     println(map1("c"))
26     map1.remove("c")
27     println(map1.getOrElse("c", 0))
28
29     map1 -= "d"
30     println(map1)
31
32     println("====================")
33
34     // 4. 修改元素
35     map1.update("c", 5)
36     map1.update("e", 10)
37     println(map1)
38
39     println("====================")
40
41     // 5. 合并两个Map
42     val map2: Map[String, Int] = Map("aaa" -> 11, "b" -> 29, "hello" -> 5)
43 //    map1 ++= map2
44     println(map1)
45     println(map2)
46
47     println("---------------------------")
48     val map3: Map[String, Int] = map2 ++ map1
49     println(map1)
50     println(map2)
51     println(map3)
52   }
53 }