Insert node at beginning of doubly linked list in scala

Scala program for Insert node at beginning of doubly linked list. Here problem description and other solutions.

// Scala Program For
// insert new node at beginning of doubly linked list

// Define class of linked list Node
class LinkNode(var data: Int,
	var next: LinkNode,
		var prev: LinkNode)
{
	def this(data: Int)
	{
		this(data, null, null)
	}
}
class DoublyLinkedList(var head: LinkNode)
{
	def this()
	{
		this(null)
	}
	// Insert new node at beginning position
	def insert(value: Int): Unit = {
		// Create a node
		var node: LinkNode = new LinkNode(value);
		node.next = this.head;
		// When linked list is not empty
		if (this.head != null)
		{
			this.head.prev = node;
		}
		// Make new head
		this.head = node;
	}
	// Display node element of doubly linked list
	def display(): Unit = {
		if (this.head == null)
		{
			println("Empty Linked List");
		}
		else
		{
			println("  Doubly Linked List Element :");
			// Get first node of linked list
			var temp: LinkNode = this.head;
			// iterate linked list 
			while (temp != null)
			{
				// Display node value
				print("  " + temp.data);
				// Visit to next node
				temp = temp.next;
			}
		}
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var dll: DoublyLinkedList = new DoublyLinkedList();
		// Insert following linked list nodes
		dll.insert(70);
		dll.insert(60);
		dll.insert(50);
		dll.insert(40);
		dll.insert(30);
		dll.insert(20);
		dll.insert(10);
		//  NULL <- 10 <--> 20 <--> 30 <--> 40 <--> 50 <--> 60 <--> 70->NULL
		dll.display();
	}
}

Output

  Doubly Linked List Element :
  10  20  30  40  50  60  70