scala - Scala 中的可观察 map

Question

我是 Scala 的新手。我想在修改 map 时收到通知。我认为这可以使用可观察 map 来完成。

我正在尝试定义一个如下所示的对象

var myObj = new Map[UUID, MyType] with ObservableMap[UUID,MyType]

但它没有编译说..

error: object creation impossible, since:
method iterator in trait MapLike of type => Iterator[(java.util.UUID, MyType)] is not defined
method get in trait MapLike of type (key: java.util.UUID)Option[MyType] is not defined
method -= in trait ObservableMap of type (key: java.util.UUID)this.type is marked `abstract' and `override', but no concrete implementation could be found in a base class
method += in trait ObservableMap of type (kv: (java.util.UUID, MyType))this.type is marked `abstract' and `override', but no concrete implementation could be found in a base class

为什么会这样？如何实例化 ObservableMap？

Answer 1

您需要将 ObservableMap 与具体的 map 类型混合。

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

scala> val map = new HashMap[Int, Int] with ObservableMap[Int, Int]
map: scala.collection.mutable.HashMap[Int,Int] with scala.collection.mutable.ObservableMap[Int,Int] = Map()