Bubble sort on linked list in kotlin

Kotlin program for Bubble sort on linked list. Here mentioned other language solution.

// Kotlin program for
// Bubble Sort For Linked List
class Node {
    var data : Int;
    var next : Node?;
    constructor(data : Int)
    {
        this.data = data;
        this.next = null;
    }
}
class LinkedList {
    var head : Node?;
    // Class constructors
    constructor()
    {
        this.head = null;
    }
    // Add node at the beginning of linked list
    fun insert(value : Int) : Unit
    {
        // Create a new node
        val node : Node = Node(value);
        // Add node at front
        node.next = this.head;
        // Make new head
        this.head = node;
    }
    // Display all elements
    fun display() : Unit
    {
        if (this.head != null)
        {
            var temp : Node? = this.head;
            while (temp != null)
            {
                // Display node value
                print("  " + temp.data);
                // Visit to next node
                temp = temp.next;
            }
        }
        else
        {
            println("Empty Linked list");
        }
    }
    // Perform bubble sort in single linked list
    fun bubbleSort() : Unit
    {
        if (this.head != null)
        {
            var current : Node? ;
            var status : Boolean;
            do
            {
                // Start with first node
                current = this.head;
                // Reset working status
                status = false;
                while (current != null && current.next != null)
                {
                    if (current.data > current.next!!.data)
                    {
                        // Swap node values
                        current.data = current.data + current.next!!.data;
                        current.next!!.data = current.data - current.next!!.data;
                        current.data = current.data - current.next!!.data;
                        // When node value change
                        status = true;
                    }
                    // Visit to next node
                    current = current.next;
                }
            } while (status);
        }
        else
        {
            println("Empty Linked list");
        }
    }
}
fun main(args : Array<String>) : Unit
    {
        val task : LinkedList = LinkedList();
        // Insert element of linked list
        task.insert(15);
        task.insert(5);
        task.insert(42);
        task.insert(9);
        task.insert(50);
        task.insert(7);
        print(" Before sort : ");
        // Display all node
        task.display();
        task.bubbleSort();
        print("\n After sort  : ");
        task.display();
    }

Output

 Before sort :   7  50  9  42  5  15
 After sort  :   5  7  9  15  42  50