How to Sort a List in Scala

1. Use Sorted Property to Sort List in Scala
2. Use the sortWith() Function to Sort List in Scala

This tutorial will discuss the procedure to sort the list elements in Scala.

A list is a container used to store elements in linear order. There is a class List in Scala to implement the list.

It provides several built-in functions to support its operations, such as inserting or deleting elements. Here, we will learn to sort the elements of a list in Scala.

Use Sorted Property to Sort List in Scala

We used the sorted property to sort the list elements in this example. First, we created a list with some elements and applied the property.

We also used the for loop to traverse the elements to see the sorted elements.

object MyClass {
    def main(args: Array[String]) {
        var list1   =  List("j", "b", "c")
        val sorted = list1.sorted
        for (name <- sorted) println(name)
    }
}

Output:

b
c
j

Use the sortWith() Function to Sort List in Scala

We used the sortWith() function to take a lambda expression as an argument and return the sorted result. We can use this function to sort the list in ascending and descending order.

See the example below.

object MyClass {
    def main(args: Array[String]) {
        var list1   =  List("j", "b", "c")
        val sorted = list1.sortWith((a: String, b: String)
   => a.charAt(0).toLower < b.charAt(0).toLower)
   println("--------ascending order-----------")
        for (name <- sorted) println(name)

        val sorted2 = list1.sortWith((a: String, b: String)
   => a.charAt(0).toLower > b.charAt(0).toLower)
   println("--------descending order----------")
        for (name <- sorted2) println(name)
    }
}

Output:

--------ascending order-----------
b
c
j
--------descending order----------
j
c
b

We can also use the _ (underscore) to replace the redundant variables and make the code concise for readability. See the example below.

object MyClass {
    def main(args: Array[String]) {
        var list1   =  List("mac", "apple", "dell")
        val sorted = list1.sortWith(_.length < _.length)
   println("--------ascending order-----------")
        for (name <- sorted) println(name)
    }
}

Output:

--------ascending order-----------
mac
dell
apple