why i have error in this code in "Track":

class Node $\{$

Track data;

Node prev;

Node next;

public Node$($Track data$)\{$

this.data $=$ data;

$\}$

$\}$

class DoublyCircularLinkedList $\{$

Node head;

Node tail;

$//$ Add track to the end of the playlist

public void addTrack$($Track track$)\{$

Node newNode $=$ new Node$($track$)$;

if $($head $==$ null$)\{$

head $=$ newNode;

tail $=$ newNode;

newNode.next $=$ newNode;

newNode.prev $=$ newNode;

$\}$ else $\{$

tail.next $=$ newNode;

newNode.prev $=$ tail;

newNode.next $=$ head;

head.prev $=$ newNode;

tail $=$ newNode;

$\}$

$\}$

$//$ Remove track from the playlist

public void removeTrack$($Track track$)\{$

if $($head $==$ null$)\{$

return;

$\}$

Node current $=$ head;

do $\{$

if $($current$.$data.equals$($track$))\{$

if $($current $==$ head$)\{$

head $=$ current.next;

$\}$

if $($current $==$ tail$)\{$

tail $=$ current.prev;

$\}$

current.prev.next $=$ current.next;

current.next.prev $=$ current.prev;

return;

$\}$

current $=$ current.next;

$\}$ while $($current $!=$ head$)$;

$\}$

$//$ Skip to the next track

public void skip$()\{$

if $($head $!=$ null$)\{$

head $=$ head.next;

$\}$

$\}$

$//$ Get the current track

public Track getCurrentTrack$()\{$

if $($head $!=$ null$)\{$

return head.data;

$\}$

return null;

$\}$

$//$ Display the playlist

public void displayPlaylist$()\{$

if $($head $==$ null$)\{$

System.out.println$("$Playlist is empty."$)$;

return;

$\}$

Node current $=$ head;

do $\{$

System.out.println$($current$.$data$)$;

current $=$ current.next;

$\}$ while $($current $!=$ head$)$;

$\}$

$\}$