Definition and usage of List in Scala

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# Declaration

Var list = List (1, 2, 3, 4) println (list)

Empty list

Var foo = List () println (foo) var bar = Nilprintln (bar)::

The:: (two colons) operators are joined to the right, and if you want to build a list List (1, 2, 3, 4), you can actually use the following way, where Nil represents an empty list.

Scala > 1::2::3::4::Nilres6: List [Int] = List (1,2,3,4)

The list has the concept of head and tail, head returns the first element of the list, tail returns a list containing elements other than the first element, the head is an element, and the tail is still a list.

Scala > a.tailres3: List [String] = List (b, c)

# isEmpty

IsEmpty returns when the list is empty

Println (foo.head) var bar = Nilprintln (bar.isEmpty)

#: three colon

:: operator joins different lists to get new lists

Scala > val a = "a":: "b":: "c":: Nila: List [String] = List (a, b, c) scala > val b = 1::2::3::Nilb: List [Int] = List (1,2,3) scala > val c = a:::bc: List [Any] = List (a, b, c, 1,2,3) "definition and usage of List in Scala". Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!