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This article mainly introduces the differences between scala::, +:,::, +, what is introduced in the article is very detailed, has a certain reference value, interested friends must read it!

The difference and relation of the four operators

:: this method is called cons, which means to construct, append data to the header of the queue and create a new list. The usage is x::list, where x is the element added to the header. Whether x is a list or not, it will only become the first element of the newly generated list, that is, the length of the newly generated list is + 1 (btw, x::list is equivalent to list.:: (x)).

: + and +: the difference between the two is that the + method is used to append elements to the tail, and the +: method is used to append elements to the header, which is similar to::, but:: can be used for pattern match, while +: is not. As for +: and: +, just remember that colons are always close to the collection type and OK.

+ + this method is used to join two sets, list1++list2.

: this method can only be used to join two collections of List type

Specific example scala > "A":: "B": Nilres0: List [String] = List (A, B) scala > "A" +: "B" +: Nilres1: List [String] = List (A, B) scala > Nil:+ "A": + "B" res2: List [String] = List (A, B) scala > res0 + + res1res3: List [String] = List (A, B, A, B) scala > res0:: res1res4: List [String] = List (A, B, A) B) scala > res0:: res1res5: List [java.io.Serializable] = List (List (A, B), A, B) these are all the contents of the article "what are the differences in scala::, +:,::, +" Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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