Question: Create a new method name removeLast inside SinglyLinkedList class to remove the last element in the linkedlist. DON'T CREATE A NEW SINGLYLINKEDLIST CLASS, USE THE
Create a new method name removeLast inside SinglyLinkedList class to remove the last element in the linkedlist. DON'T CREATE A NEW SINGLYLINKEDLIST CLASS, USE THE PROVIDED ONE BELOW.
public class SinglyLinkedList
//---------------- nested Node class ----------------
/**
* Node of a singly linked list, which stores a reference to its
* element and to the subsequent node in the list (or null if this
* is the last node).
*/
private static class Node
/** The element stored at this node */
private E element; // reference to the element stored at this node
/** A reference to the subsequent node in the list */
private Node
/**
* Creates a node with the given element and next node.
*
* @param e the element to be stored
* @param n reference to a node that should follow the new node
*/
public Node(E e, Node
element = e;
next = n;
}
// Accessor methods
/**
* Returns the element stored at the node.
* @return the element stored at the node
*/
public E getElement() { return element; }
/**
* Returns the node that follows this one (or null if no such node).
* @return the following node
*/
public Node
// Modifier methods
/**
* Sets the node's next reference to point to Node n.
* @param n the node that should follow this one
*/
public void setNext(Node
} //----------- end of nested Node class -----------
// instance variables of the SinglyLinkedList
/** The head node of the list */
private Node
/** The last node of the list */
private Node
/** Number of nodes in the list */
private int size = 0; // number of nodes in the list
/** Constructs an initially empty list. */
public SinglyLinkedList() { } // constructs an initially empty list
// access methods
/**
* Returns the number of elements in the linked list.
* @return number of elements in the linked list
*/
public int size() { return size; }
/**
* Tests whether the linked list is empty.
* @return true if the linked list is empty, false otherwise
*/
public boolean isEmpty() { return size == 0; }
/**
* Returns (but does not remove) the first element of the list
* @return element at the front of the list (or null if empty)
*/
public E first() { // returns (but does not remove) the first element
if (isEmpty()) return null;
return head.getElement();
}
/**
* Returns (but does not remove) the last element of the list.
* @return element at the end of the list (or null if empty)
*/
public E last() { // returns (but does not remove) the last element
if (isEmpty()) return null;
return tail.getElement();
}
// update methods
/**
* Adds an element to the front of the list.
* @param e the new element to add
*/
public void addFirst(E e) { // adds element e to the front of the list
head = new Node<>(e, head); // create and link a new node
if (size == 0)
tail = head; // special case: new node becomes tail also
size++;
}
/**
* Adds an element to the end of the list.
* @param e the new element to add
*/
public void addLast(E e) { // adds element e to the end of the list
Node
if (isEmpty())
head = newest; // special case: previously empty list
else
tail.setNext(newest); // new node after existing tail
tail = newest; // new node becomes the tail
size++;
}
/**
* Removes and returns the first element of the list.
* @return the removed element (or null if empty)
*/
public E removeFirst() { // removes and returns the first element
if (isEmpty()) return null; // nothing to remove
E answer = head.getElement();
head = head.getNext(); // will become null if list had only one node
size--;
if (size == 0)
tail = null; // special case as list is now empty
return answer;
}
}
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