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Cuauhtli
Asked: 2022-08-18 18:46:32 +0800 CST 2022-08-18 18:46:32 +0800 CST

Update a ListBuffer with the values ​​of another list

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How can I update (but not add, or append ), items from one list to another in Scala?

It finds me programming in Scala, and I try to update a ListBuffer with the values ​​I have from another list:

val allThemes: ListBuffer[MyType] = ListBuffer[MyType]()

val pageSize = 500
var pageToken = ""

do {
  val response: Response = ...
  val dataThemes: List[MyType] = response.items  // Estos son los nuevos valores
  pageToken = response.next_page_token

  // Aquí tratataba según de actualizar una lista con 
  // nuevos valores
  if (dataThemes.nonEmpty)
    allThemes += dataThemes  // Aquí me da un error de tipo

} while (...)

allThemes.toList

But it sends me a type error because it turns out that it doesn't do an update as I thought, but an "append", and therefore the types are different.

type mismatch; found ListBuffer[List[MyType]] Required: ListBuffer[MyType]

I know I can iterate over those values, and then do a +=, but I don't hear a "fancy", friendly option.

scala

1 Answers

  1. Best Answer

    Lol, case closed.

    I just read the official documentation, and it mentions that you can do that with a ++=:

    lista ++= listaConElementosAanadir

    https://www.scala-lang.org/api/2.13.6/scala/collection/mutable/ListBuffer.html#++=(xs:scala.collection.IterableOnce[A]):Growable.this.type

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