Write a method in the LList class that finds the first occurrence of a given value in a linked list and if found, returns its position in the list, otherwise returns $0.$ The targeted value should be a parameter of the method $($of the generic type T$).$ Include testing of the method in the main method of the LList $.$ package lab$11$;

$/**$

A doubly$-$linked implementation of the ADT list.

@author Frank M$.$ Carrano

@author Joseph Erickson

@version $4\mathrm{.}0$

$*/$

public class DoublyLList implements ListInterface

$\{$

private Node firstNode; $//$ Reference to first node

private int numberOfEntries;

public DoublyLList$()$

$\{$

initializeDataFields$()$;

$\}//$ end default constructor

public final void clear$()//$ Note the final method

$\{$

initializeDataFields$()$;

$\}//$ end clear

public void add$($T newEntry$)//$ OutOfMemoryError possible

$\{$

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

if $($isEmpty$())$

firstNode $=$ newNode;

else $//$ Add to end of non$-$empty list

$\{$

Node lastNode $=$ getNodeAt$($numberOfEntries$)$;

lastNode.setNextNode$($newNode$)$; $//$ Make last node reference new node

newNode.setPreviousNode$($lastNode$)$;

$\}//$ end else

numberOfEntries$++$;

$\}//$ end add

public void add$($int newPosition, T newEntry$)//$ OutOfMemoryError possible

$\{$

if $(($newPosition $>=1)$ && $($newPosition $<=$ numberOfEntries $+1))$

$\{$

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

if $($newPosition $==1)//$ Case $1$

$\{$

newNode.setNextNode$($firstNode$)$;

if $($firstNode $!=$ null$)$

firstNode.setPreviousNode$($newNode$)$;

firstNode $=$ newNode;

$\}//$ end if

else $//$ Case $2$: List is not empty

$\{//$ and newPosition $>1$

Node nodeBefore $=$ getNodeAt$($newPosition $-1)$;

Node nodeAfter $=$ nodeBefore.getNextNode$()$;

newNode.setNextNode$($nodeAfter$)$;

newNode.setPreviousNode$($nodeBefore$)$;

nodeBefore.setNextNode$($newNode$)$;

if $($nodeAfter $!=$ null$)$

nodeAfter.setPreviousNode$($newNode$)$;

$\}//$ end else

numberOfEntries$++$;

$\}//$ end if

else

throw new IndexOutOfBoundsException$("$Illegal position given to add operation."$)$;

$\}//$ end add

public T remove$($int givenPosition$)$

$\{$

T result $=$ null; $//$ Return value

if $(($givenPosition $>=1)$ && $($givenPosition $<=$ numberOfEntries$))$

$\{$

assert $!$isEmpty$()$;

if $($givenPosition $==1)//$ Case $1$: Remove first entry

$\{$

result $=$ firstNode.getData$()$; $//$ Save entry to be removed

firstNode $=$ firstNode.getNextNode$()$;

firstNode.setPreviousNode$($null$)$;

$\}//$ end if

else $//$ Case $2$: Not first entry

$\{$

Node nodeBefore $=$ getNodeAt$($givenPosition $-1)$;

Node nodeToRemove $=$ nodeBefore.getNextNode$()$;

Node nodeAfter $=$ nodeToRemove.getNextNode$()$;

nodeBefore.setNextNode$($nodeAfter$)$;

if $($nodeAfter $!=$ null$)$

nodeAfter.setPreviousNode$($nodeBefore$)$;

result $=$ nodeToRemove.getData$()$; $//$ Save entry to be removed

$\}//$ end else

numberOfEntries$--$;

return result;

$\}//$ end if

else

throw new IndexOutOfBoundsException$("$Illegal position given to remove operation."$)$;

$\}//$ end remove

public T replace$($int givenPosition, T newEntry$)$

$\{$

if $(($givenPosition $>=1)$ && $($givenPosition $<=$ numberOfEntries$))$

$\{$

assert $!$isEmpty$()$;

Node desiredNode $=$ getNodeAt$($givenPosition$)$;

T originalEntry $=$ desiredNode.getData$()$;

desiredNode.setData$($newEntry$)$;

return originalEntry;

$\}//$ end if

else

throw new IndexOutOfBoundsException$("$Illegal position given to replace operation."$)$;

$\}//$ end replace

public T getEntry$($int givenPosition$)$

$\{$

if $(($givenPosition $>=1)$ && $($givenPosition $<=$ numberOfEntries$))$

$\{$

assert $!$isEmpty$()$;

return getNodeAt$($givenPosition$).$getData$()$;

$\}//$ end if

else

throw new IndexOutOfBoundsException$("$Illegal position given to getEntry operation."$)$;

$\}//$ end getEntry

public boolean contains$($T anEntry$)$

$\{$

boolean found $=$ false;

Node currentNode $=$ firstNode;

while $(!$found && $($currentNode $!=$ null$))$

$\{$

if $($anEntry$.$equals$($currentNode$.$getData$()))$

found $=$ true;

else

currentNode $=$ currentNode.getNextNode$()$;

$\}//$ end while

return found;

$\}//$ end contains

public int getLength$()$

$\{$

return numberOfEntries;

$\}//$ end getLength

public boolean isEmpty$()$

$\{$

boolean result;

if $($numberOfEntries $==0)//$ Or getLength$()==0$

$\{$

assert firstNode $==$ null;

result $=$ true;

$\}//$ end if

else

$\{$

assert firstNode $!=$ null;

result $=$ false;

$\}//$ end else

return result;

$\}//$ end isEmpty

public T$[]$ toArray$()$

$\{$

$//$ The cast is safe because the new array contains null entries

@SuppressWarnings$("$unchecked$")$

T$[]$ result $=($T$[])$new Object$[$numberOfEntries$]$; $//$ Unchecked cast

int index $=0$;

Node currentNode $=$ firstNode;

while $(($index $<$ numberOfEntries$)$ && $($currentNode $!=$ null$))$

$\{$

result$[$index$]=$ currentNode.getData$()$;

currentNode $=$ currentNode.getNextNode$()$;

index$++$;

$\}//$ end while

return result;

$\}//$ end toArray

$//$ Initializes the class's data fields to indicate an empty list.

private void initializeDataFields$()$

$\{$