Double-ended queue Implementation and Doubly linked list in Java

Double-ended queue Implementation

package com.java2novice.ds.queue;

import java.util.ArrayList;

import java.util.List;

public class DoubleEndedQueueImpl

{

 private List deque = new ArrayList();

    public void insertFront(int item)

    {

        System.out.println("adding at front: "+item);

        deque.add(0,item);

        System.out.println(deque);

    }

    public void insertRear(int item)

    {

        System.out.println("adding at rear: "+item);

        deque.add(item);

        System.out.println(deque);

    }

     public void removeFront()

     {

        if(deque.isEmpty())

        {

            System.out.println("Deque underflow!! unable to remove.");

            return;

        }

        int rem = deque.remove(0);

        System.out.println("removed from front: "+rem);

        System.out.println(deque);

    }

     public void removeRear()

    {

        if(deque.isEmpty())

       {

            System.out.println("Deque underflow!! unable to remove.");

            return;

        }

        int rem = deque.remove(deque.size()-1);

        System.out.println("removed from front: "+rem);

        System.out.println(deque);

    }

        public int peakFront()

        {

        int item = deque.get(0);

        System.out.println("Element at first: "+item);

        return item;

    }

    public int peakRear()

   {

        int item = deque.get(deque.size()-1);

        System.out.println("Element at rear: "+item);

        return item;

    }

     public static void main(String a[])

    {

        DoubleEndedQueueImpl deq = new DoubleEndedQueueImpl();

        deq.insertFront(34);

        deq.insertRear(45);

        deq.removeFront();

        deq.removeFront();

        deq.removeFront();

        deq.insertFront(21);

        deq.insertFront(98);

        deq.insertRear(5);

        deq.insertFront(43);

        deq.removeRear();

    }

}

Double-ended queue implementation using Doubly linked list

package com.java2novice.ds.queue;

public class DequeDblLinkedListImpl

{

    private Node front;

    private Node rear;

    public void insertFront(T item)

    {

        System.out.println("adding at front: "+item);

        Node nd = new Node();

        nd.setValue(item);

        nd.setNext(front);

        if(front != null) front.setPrev(nd);

        if(front == null) rear = nd;

        front = nd;

    }

     public void insertRear(T item)

     {

        System.out.println("adding at rear: "+item);

        Node nd = new Node();

        nd.setValue(item);

        nd.setPrev(rear);

        if(rear != null) rear.setNext(nd);

        if(rear == null) front = nd;

               rear = nd;

    }

     public void removeFront()

     {

        if(front == null)

         {

            System.out.println("Deque underflow!! unable to remove.");

            return;

        }

        Node tmpFront = front.getNext();

        if(tmpFront != null) tmpFront.setPrev(null);

        if(tmpFront == null) rear = null;

        System.out.println("removed from front: "+front.getValue());

        front = tmpFront;

    }

     public void removeRear()

     {

        if(rear == null)

        {

            System.out.println("Deque underflow!! unable to remove.");

            return;

        }

        Node tmpRear = rear.getPrev();

        if(tmpRear != null) tmpRear.setNext(null);

        if(tmpRear == null) front = null;

        System.out.println("removed from rear: "+rear.getValue());

        rear = tmpRear;

    }

       public static void main(String a[])

       {

        DequeDblLinkedListImpl deque = new                    DequeDblLinkedListImpl();

        deque.insertFront(34);

        deque.insertFront(67);

        deque.insertFront(29);

        deque.insertFront(765);

        deque.removeFront();

        deque.removeFront();

        deque.removeFront();

        deque.insertRear(43);

        deque.insertRear(83);

        deque.insertRear(84);

        deque.insertRear(546);

        deque.insertRear(356);

        deque.removeRear();

        deque.removeRear();

        deque.removeRear();

        deque.removeRear();

        deque.removeFront();

        deque.removeFront();

        deque.removeFront();

    }

}

class Node

{

    private Node prev;

    private Node next;

    private T value;

    public Node getPrev()

    {

        return prev;

    }

    public void setPrev(Node prev)

   {

        this.prev = prev;

    }

    public Node getNext()

   {

        return next;

    }

    public void setNext(Node next)

    {

        this.next = next;

    }

    public T getValue()

   {

        return value;

    }

    public void setValue(T value)

    {

        this.value = value;

    }

}