scala集合三大类(seq序列,set集,map映射)——map映射

map映射：

scala> import scala.collection.mutable.HashMap._

import scala.collection.mutable.HashMap._

 

scala> val map1 = new HashMap[String,Int]()

map1: scala.collection.mutable.HashMap[String,Int] = HashMap()

 

scala> map1("scala") = 1

 

scala> map1

res83: scala.collection.mutable.HashMap[String,Int] = HashMap(scala -> 1)

 

scala> map1 += (("java",2))                 //使用+=添加一个元素

res84: map1.type = HashMap(java -> 2, scala -> 1)

 

scala> map1

res85: scala.collection.mutable.HashMap[String,Int] = HashMap(java -> 2, scala -> 1)

 

scala> map1 += (("python",3),("web",4))　　　　//添加多个元素

            ^

       warning: method += in trait Growable is deprecated (since 2.13.0): Use `++=` (addAll) instead of varargs `+=`

res86: map1.type = HashMap(python -> 3, java -> 2, web -> 4, scala -> 1)

 

scala> map1

res88: scala.collection.mutable.HashMap[String,Int] = HashMap(python -> 3, java -> 2, web -> 4, scala -> 1)

 

scala> map1 -= ("web")　　　　　　　　//使用 -= 移除map里面的一个元素

res89: map1.type = HashMap(python -> 3, java -> 2, scala -> 1)

 

scala> map1.remove("java")　　　　　　//移除一个元素

res90: Option[Int] = Some(2)

 

scala> map1.put("c++",6)　　　　　　//添加一个元素 put 操作方法实现

res92: Option[Int] = None

 

scala> map1

res93: scala.collection.mutable.HashMap[String,Int] = HashMap(python -> 3, c++ -> 6, scala -> 1)