CODEWITHSUNDEEP
listscalaconcatenation
masiboo
masiboo

Reputation: 4719

scala how to concatenate two list of class

I have this class

 case class User(var userId: Int, var userName: String, var email:      
String, var password: String) {
  def this() = this(0, "", "", "")
}

I have two list same User type list teamMembers usrList

I want to concatenate both into one teamMembers. I don't know how to do it so tried as:

 teamMembers:::usrList 
 teamMembers = teamMembers:::usrList
 teamMembers++usrList
 teamMembers = teamMembers++usrList

Nothing seems to be working. I guess it must be easy. Just having difficulties to understand scala doc. How to concatenate them into one.

Upvotes: 0

Views: 266

Answers (2)

elm
elm

Reputation: 20415

Consider the operator ++= for appending a list to a (mutable) list; for instance for

case class User(var userId: Int = 0, 
                var userName: String = "", 
                var email: String = "", 
                var password: String = "")

and 

var teamMembers = List ( User(0), User(1) )
val usrList = List( User(3) )

we have that 

teamMembers ++= usrList

and so

teamMembers
List[User] = List(User(0,,,), User(1,,,), User(3,,,))

Another approach involves 

teamMembers = List(teamMembers, usrList).flatten

Namely, we create a list of lists and flatten them up onto a list.

Upvotes: 0

dhg
dhg

Reputation: 52681

It's unclear what you're problem actually is, the usage is pretty straightforward:

val a = List(1,2,3)
val b = List(4,5,6)
val c = a ::: b  // List(1, 2, 3, 4, 5, 6)
val d = a ++ b   // List(1, 2, 3, 4, 5, 6)

Maybe the thing you're missing is that concatenation produces a new list that is the concatenation of the previous two? Or that you can't reassign vals so you need to assign to a fresh variable name?

Upvotes: 1

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