Convert singly linked list to circular list in scala

Scala program for Convert singly linked list to circular list. Here problem description and other solutions.

// Scala program for
// Convert singly linked list into circular list
// Define class of linked list Node
class LinkNode(var data: Int,
	var next: LinkNode)
{
	def this(data: Int)
	{
		this(data, null);
	}
}
class LinkedList(var head: LinkNode)
{
	// Class constructor
	def this()
	{
		this(null);
	}
	// Check circular linked list or not
	// Note that this function is not capable to detect loop
	def isCircular(): Boolean = {
		if (this.head == null)
		{
			// Case when linked list is empty
			return false;
		}
		else
		{
			var temp: LinkNode = this.head;
			while (temp != null)
			{
				// Visit to next node
				temp = temp.next;
				if (temp == this.head)
				{
					// When detecting circular node
					return true;
				}
			}
			// When not circular linked list
			return false;
		}
	}
	// Display node element of linked list
	def display(): Unit = {
		if (this.head == null)
		{
			println("Empty Linked List");
		}
		else
		{
			print("Linked List Element :");
			var temp: LinkNode = this.head;
			// Iterate linked list
			while (temp != null)
			{
				// Display node
				print("  " + temp.data);
				// Visit to next node
				temp = temp.next;
				if (temp == head)
				{
					// Stop iteration
					return;
				}
			}
			println();
		}
	}
	// Coverted circular Linked list
	def makeCircular(): Unit = {
		if (this.head == null)
		{
			println("Empty Linked List");
		}
		else
		{
			var temp: LinkNode = this.head;
			// Find last node
			while (temp.next != null)
			{
				temp = temp.next;
				if (temp == this.head)
				{
					// Already circular Linked list
					return;
				}
			}
			// Connect last node to first node
			temp.next = this.head;
		}
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var ll: LinkedList = new LinkedList();
		// Insert element of linked list
		ll.head = new LinkNode(1);
		ll.head.next = new LinkNode(2);
		ll.head.next.next = new LinkNode(3);
		ll.head.next.next.next = new LinkNode(4);
		ll.head.next.next.next.next = new LinkNode(5);
		ll.head.next.next.next.next.next = new LinkNode(6);
		ll.head.next.next.next.next.next.next = new LinkNode(7);
		ll.display();
		if (ll.isCircular())
		{
			println("Circular Yes");
		}
		else
		{
			println("Circular No");
		}
		println("After Convert");
		ll.makeCircular();
		if (ll.isCircular())
		{
			println("Circular Yes");
		}
		else
		{
			println("Circular No");
		}
	}
}

Output

Linked List Element :  1  2  3  4  5  6  7
Circular No
After Convert
Circular Yes