scala - 将不可变集合转换为可变集合

Question

collection.immutable.Set转换为的最佳方法是collection.mutable.Set什么？

Answer 1

scala> var a=collection.mutable.Set[Int](1,2,3)                              
a: scala.collection.mutable.Set[Int] = Set(1, 2, 3)

scala> var b=collection.immutable.Set[Int](1,2,3)
b: scala.collection.immutable.Set[Int] = Set(1, 2, 3)

scala> collection.mutable.Set(b.toArray:_*)      
res0: scala.collection.mutable.Set[Int] = Set(1, 2, 3)

scala> collection.mutable.Set(b.toSeq:_*)  
res1: scala.collection.mutable.Set[Int] = Set(1, 2, 3)

scala> collection.mutable.Set(b.toList:_*)
res2: scala.collection.mutable.Set[Int] = Set(1, 2, 3)

Answer 2

开始Scala 2.13，通过工厂建设者申请.to(factory)：

Set(1, 2, 3).to(collection.mutable.Set)
// collection.mutable.Set[Int] = HashSet(1, 2, 3)

之前Scala 2.13和开始Scala 2.10：

Set(1, 2, 3).to[collection.mutable.Set]
// collection.mutable.Set[Int] = Set(1, 2, 3)