Category: Java Samples

This is a Linked List object which can take any kind of input as a Node and organize it as an arrayList would organize it.

The Object inherits from the interfaces Stack and Queue, written by professor Adam Smith, provided at the bottom!

Enjoy!

/**
 * Linked List object which implements the Stack and Queue interfaces, allowing users to create
 * a linked list of Nodes
 *
 * @version 1.0
 * @author AidanTakami
 *
 */
public class LinkedList implements Queue, Stack{
	//Fields
	public  Node head;
	public  Node tail;
	public  int size;

//*************************
//LinkedList
//*************************

	/**
	 * The constructor for the LinkedList which takes the head and the tail Node
	 * @param Node head
	 * @param Node tail
	 * @since 1.0
	 */
	public LinkedList(Node head, Node tail){
		this.head = head;
		this.tail = tail;
		this.head.setNext(this.tail);
		size = 2;
	}

	/**
	 * adds the E value to the head of the LinkedList
	 *
	 * @param value  the value to be added to the tail
	 * @since 1.0
	 */
	public void addtoHead(E value){
		Node newNode = new Node(value);
		newNode.setNext(head);
		head = newNode;
		size++;
	}

	/**
	 * adds the E value to the tail of the LinkedList
	 *
	 * @param value  the value to be added to the tail
	 * @since 1.0
	 */
	public void addToTail(E value){
		Node newNode = new Node(value);
		tail.setNext(newNode);
		tail = newNode;
		size++;
	}

	/**
	 * Checks to see if the specified value is contained
	 *
	 * @param value  the value to be checked for within the LinkedList
	 * @return boolean  whether or not the value is contained
	 * @since 1.0
	 */
	public boolean contains(E value){
		//if head == value, return true
		if(head.getData().equals(value)) return true;

		Node inspect = head.getPointer();
		//otherwise
		for(int rep = 1; rep  0){
			Node oldHead = head;
			head = oldHead.getPointer();
			size--;
			return (E )oldHead.getData();
		}
		else return null;
	}

	/**
	 * toString method for the LinkedList
	 */
	@Override
	public String toString(){
		//creates string to be returned
		String listString = (" " + head.toString());

		//creates node to be changed and cycle through LinkedList
		Node subject = head;

		//loop which adds each next node to the String
		for(int rep = 0; rep  " + subject + " ");
			}
		}

		//returns the String
		return listString;
	}

//*************************
//Queue Methods
//*************************

	/**
	 * sets the head to the 2nd item in LinkedList and then returns the data
	 * of the previous head
	 *
	 * @since 1.0
	 */
	public E dequeue(){
		Node oldHead = head;
		head = oldHead.getPointer();
		size--;
		return (E )oldHead.getData();
	}

	/**
	 * Adds a Node to the end of the queue and sets that as the new tail
	 *
	 * @param Object value the object to be added to the end
	 * @since 1.0
	 */
	public void enqueue(Object value){
		Node addOn = new Node(value);
		tail.setNext(addOn);
		tail = tail.getPointer();
		size++;
	}

	/**
	 * Peeks at the head of the Queue or Stack
	 *
	 * @since 1.0
	 */
	public E peek(){
		return (E )head.getData();
	}

//*************************
//Stack Methods
//*************************

	/**
	 * removes an item from the head of the Stack, and returns it
	 *
	 * @return the value removed
	 */
	public E pop(){
		Node oldHead = head;
		head = head.getPointer();
		size--;
		return (E )oldHead.getData();
	}

	/**
	 * adds an item to the top of the Stack
	 *
	 * @param value  the value to be added
	 */
	public void push(Object value){
		Node newHead = new Node(value);
		newHead .setNext(head);
		head = newHead;
		size++;
	}

//*************************
//Node Object
//*************************

	/**
	 * Node object which contains a constructor method and a toString.
	 * Node holds an E value as well as a pointer to the next node in a LinkedList.
	 *
	 * @author AidanTakami
	 * @param 
	 * @since 1.0
	 */
	public static class Node{
		//Field
		E data;
		Node nextNode = null;

		/**
		 * Constructor for the Node object. takes the data which will be stored in the Node.
		 * @param data
		 * @since 1.0
		 */
		public Node(E data){
			this.data = data;
		}

		/**
		 * toString Method for the Node object.
		 *
		 * @since 1.0
		 */
		@Override
		public String toString(){
			return "(" + data + ")";
		}

		/*
		 * Returns the Node nextNode of the Node, which is the next Node in the sequence
		 */
		private Node getPointer(){
			return nextNode;
		}

		/*
		 * Returns the data of the Node
		 */
		private E getData(){
			return data;
		}

		/*
		 * Sets the nextNode of the node, only to be accessible by the LinkedList object
		 */
		private void setNext(Node next){
			nextNode = next;
		}

	}

/**
 * This is an interface for a Queue. An object which implements this interface
 * is thus a "first in, first out", or "FIFO" structure. It can enqueue to the
 * end, dequeue from the front, or peek at the front.
 *
 * @author Adam Smith
 * @version 1.0
 */
public interface Queue {
/**
* Removes an item from the front of the queue.
*
* @return the value removed
*/

public E dequeue();

/**
* Adds an item to the end of the queue.
*
* @param value the value to be enqueued
*/

public void enqueue(E value);

/**
* Checks item at the front of the queue, without altering the queue.
*
* @return the value checked
*/

public E peek();
}

/**
 * This is an interface for a Stack. An object which implements this interface
 * is thus a "first in, last out", or "FILO" structure. It can push to the top,
 * pop from the top, or peek at the top.
 *
 * @author Adam Smith
 * @version 1.0
 */

public interface Stack {
	/**
	 * Checks item at the top of the stack, without altering the stack.
	 *
	 * @return the value checked
	 */

	public E peek();

	/**
	 * Removes an item from the top of the stack.
	 *
	 * @return the value removed
	 */

	public E pop();

	/**
	 * Adds an item to the top of the stack.
	 *
	 * @param value  the value to be enqueued
	 */

	public void push(E value);
}