Scala List Append to End

Scala provides a powerful collection library that includes Lists, which are immutable sequences of elements. In this tutorial, we will look at how to append elements to the end of a List in Scala.

Method 1: Using the ::: operator

Scala provides the ::: (pronounced "cons") operator to concatenate two Lists. We can use this operator to append elements to the end of a List.

val list1 = List(1, 2, 3)
val list2 = List(4, 5, 6)

val newList = list1 ::: list2

println(newList) // List(1, 2, 3, 4, 5, 6)

In the above example, we have two Lists list1 and list2. We use the ::: operator to concatenate list1 and list2 and store the result in newList.

Method 2: Using the List.:::() method

Scala provides a method called :::() on the List class that concatenates two Lists. We can use this method to append elements to the end of a List.

val list1 = List(1, 2, 3)
val list2 = List(4, 5, 6)

val newList = list1.:::(list2)

println(newList) // List(4, 5, 6, 1, 2, 3)

In the above example, we have two Lists list1 and list2. We use the :::() method on list1 and pass list2 as its argument. This method concatenates the two Lists and returns the result, which we store in newList.

Method 3: Using the List.::() and List.:::() methods

Scala's List class provides two methods to add elements to the beginning of a List, :: (pronounced "cons") and :::(). We can use these methods to append elements to the end of a List by first creating a new List with the elements to be appended and then concatenating it with the original List.

val list1 = List(1, 2, 3)
val list2 = List(4, 5, 6)

val appendedList = 7 :: 8 :: Nil // create a new List with elements 7 and 8
val newList = list1 ::: appendedList ::: list2 // concatenate the three Lists

println(newList) // List(1, 2, 3, 7, 8, 4, 5, 6)

In the above example, we create a new List appendedList with elements 7 and 8 using the :: operator and Nil. We then concatenate list1, appendedList, and list2 using the ::: method to append the elements in appendedList to the end of list1.

Conclusion

In this tutorial, we looked at three different methods to append elements to the end of a List in Scala. We used the ::: operator, :::() method, and :: and :::() methods together to achieve the desired result. Scala's collection library provides many more operations on Lists and other collection types that can be used to manipulate and transform data.