Scala 在从可迭代创建集合时是否必须转换为 Seq？
也许我（再次）喊错了树，但如果通常的做法是将属性类型为 scala.collection.immutable.Set[A]，那么您将如何创建其中之一给定一个 scala.Iterable[A] ？ 例如：
class ScalaClass {
private var s: scala.collection.immutable.Set[String]
def init(): Unit = {
val i = new scala.collection.mutable.HashSet[String]
//ADD SOME STUFF TO i
s = scala.collection.immutable.Set(i) //DOESN'T WORK
s = scala.collection.immutable.Set(i toSeq : _ *) //THIS WORKS
}
}
有人可以解释为什么有必要通过 Seq 创建不可变集（或者如果不是，那么我该怎么做）？
Perhaps I am barking up the wrong tree (again) but if it is normal practice to have a property typed as a scala.collection.immutable.Set[A], then how would you create one of these given a scala.Iterable[A]? For example:
class ScalaClass {
private var s: scala.collection.immutable.Set[String]
def init(): Unit = {
val i = new scala.collection.mutable.HashSet[String]
//ADD SOME STUFF TO i
s = scala.collection.immutable.Set(i) //DOESN'T WORK
s = scala.collection.immutable.Set(i toSeq : _ *) //THIS WORKS
}
}
Can someone explain why it is necessary to create the immutable set via a Seq (or if it is not, then how do I do it)?
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基本上是因为您正在通过 Set 的伴随对象中应用的“规范工厂方法”创建不可变的 Set，该对象采用序列或“varargs”（如 Set(a,b,c) 中）。 请参阅此：
http://scala- tools.org/scaladocs/scala-library/2.7.1/scala/collection/immutable/Set$object.html
我认为标准库中没有另一个可以做到这一点。
Basically because you're creating the immutable Set through the "canonical factory method" apply in Set's companion object, which takes a sequence, or "varargs" (as in Set(a,b,c)). See this:
http://scala-tools.org/scaladocs/scala-library/2.7.1/scala/collection/immutable/Set$object.html
I don't think there is another to do it in the standard library.
它将制作一个不可变的副本：
It will make an immutable copy: