Scala

Question

据我了解，我们可以将一个空的可变 HashMap 初始化为

var keyCountsMap :scala.collection.mutable.Map[Any, Int] = scala.collection.mutable.Map[Any, Int]()

但是如何将这个 HasMap 初始化为同步的呢？我试过了

var keyCountsMap :scala.collection.mutable.SynchronizedMap[Any, Int] = scala.collection.mutable.Map[Any, Int]()

但我收到以下错误：

type mismatch; found : scala.collection.mutable.Map[Any,Int]
required: scala.collection.mutable.SynchronizedMap[Any,Int]

Answer 1

您可以混入 SynchronizedMap ( deprecated in 2.11 )

    var keyCountsMap = new scala.collection.mutable.HashMap[Any, Int]() with scala.collection.mutable.SynchronizedMap[Int, Int]

Answer 2

如果您查看文档，您会看到：

This class should be used as a mixin. It synchronizes the Map functions of the class into which it is mixed in.

和

Synchronization via traits is deprecated as it is inherently unreliable. Consider java.util.concurrent.ConcurrentHashMap as an alternative.

Scala - 初始化一个空的可变 SynchronizedHashMap