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What the difference between List.empty, List() and new List()? When should I use which?
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An empty collection is actually a collection, but there aren't any elements in it yet. null means no collection exists at all.
Actually, it will not create a new ArrayList in memory, instead it will replace the old list.
list is a global name that may be overridden during runtime. list() calls that name. [] is always a list literal.
The emptyList() method of Java Collections returns the list with no elements. This method is immutable.
First of all, new List() won't work, since the List class is abstract. The other two options are defined as follows in the List object:
override def empty[A]: List[A] = Nil override def apply[A](xs: A*): List[A] = xs.toList I.e., they're essentially equivalent, so it's mostly a matter of style. I prefer to use empty because I find it clearer, and it cuts down on parentheses.
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