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84 lines
1.6 KiB
84 lines
1.6 KiB
package net.jrtechs.www.DataStructures.Lists.Queue;
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import net.jrtechs.www.DataStructures.Node;
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/**
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* Data structure which stores objects in a linked
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* list where objects inserted first are removed first,
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* and where objects inserted last are removed last.
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*
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* @author Jeffery Russell 8-26-18
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* @param <E> generic data type
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*/
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public class Queue<E> implements IQueue<E>
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{
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/** Head node */
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private Node<E> head;
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/**Stored tail to make insertions o(1) */
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private Node<E> tail;
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/**
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* Creates an empty queue
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*/
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public Queue()
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{
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this.head = null;
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this.tail = null;
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}
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/**
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* Creates a queue with a single element in it
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*
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* @param element object to add to queue
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*/
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public Queue(E element)
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{
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this.head = new Node<>(element);
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this.tail = head;
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}
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/**
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* Adds a single element to the queue
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*
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* @param element object to add
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*/
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@Override
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public void enqueue(E element)
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{
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Node<E> newElement = new Node<>(element);
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if(this.tail == null)
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{
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this.head = newElement;
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this.tail = newElement;
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}
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else
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{
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this.tail.setNext(newElement);
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this.tail = newElement;
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}
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}
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/**
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* Removes the element from the front of the queue
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*
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* @return element removed
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*/
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@Override
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public E dequeue()
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{
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if(this.head != null)
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{
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E temp = this.head.getData();
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this.head = this.head.getNext();
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return temp;
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}
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return null;
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}
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}
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