this is my code any help woul,d be appreacited

@Override

default boolean isEmpty$()\{$

return size$()==0$;

$\}$

@Override

default boolean remove$($Object e$)\{$

int index $=$ indexOf$($e$)$;

if $($index $>=0)\{$

remove$($index$)$;

return true;

$\}$

return false;

$\}$

@Override

default boolean containsAll$($Collection c$)\{$

$//$ Implementation left as an exercise

return true;

$\}$

@Override

default boolean addAll$($Collection c$)\{$

$//$ Implementation left as an exercise

return true;

$\}$

@Override

default boolean removeAll$($Collection c$)\{$

$//$ Implementation left as an exercise

return true;

$\}$

@Override

default boolean retainAll$($Collection c$)\{$

$//$ Implementation left as an exercise

return true;

$\}$

woWayLinkedList implements MyList $\{$

private Node head, tail;

private int size;

public TwoWayLinkedList$()\{$

$\}$

public TwoWayLinkedList$($E$[]$ objects$)\{$

for $($E e : objects$)$

add$($e$)$;

$\}$

public E getFirst$()\{$

return size $==0?$ null : head.element;

$\}$

public E getLast$()\{$

return size $==0?$ null : tail.element;

$\}$

@Override

public String toString$()\{$

StringBuilder result $=$ new StringBuilder$("[")$;

Node current $=$ head;

while $($current $!=$ null$)\{$

result.append$($current$.$element$)$;

current $=$ current.next;

if $($current $!=$ null$)$ result.append$(",")$;

$\}$

result.append$("]")$;

return result.toString$()$;

$\}$

public void clear$()\{$

head $=$ tail $=$ null;

size $=0$;

$\}$

@Override

public boolean contains$($Object e$)\{$

Node current $=$ head;

while $($current $!=$ null$)\{$

if $($current$.$element.equals$($e$))\{$

return true;

$\}$

current $=$ current.next;

$\}$

return false;

$\}$

@Override

public E get$($int index$)\{$

checkIndex$($index$)$;

Node current $=$ head;

for $($int i $=0$; i $<$ index; i$++)\{$

current $=$ current.next;

$\}$

return current.element;

$\}$

@Override

public int indexOf$($Object e$)\{$

int index $=0$;

Node current $=$ head;

while $($current $!=$ null$)\{$

if $($current$.$element.equals$($e$))\{$

return index;

$\}$

current $=$ current.next;

index$++$;

$\}$

return $-1$;

$\}$

@Override

public int lastIndexOf$($E e$)\{$

int index $=-1$;

int i $=0$;

Node current $=$ head;

while $($current $!=$ null$)\{$

if $($current$.$element.equals$($e$))\{$

index $=$ i;

$\}$

current $=$ current.next;

i$++$;

$\}$

return index;

$\}$

@Override

public E set$($int index, E e$)\{$

checkIndex$($index$)$;

Node current $=$ head;

for $($int i $=0$; i $<$ index; i$++)\{$

current $=$ current.next;

$\}$

E oldElement $=$ current.element;

current.element $=$ e;

return oldElement;