Double-Ended Lists in core-java

Double-Ended List

A double-ended lists is similar to an ordinary linked list but it has one additional feature that a reference to the last link as well as the first.
The reference to the last link permits you to insert a new link directly at the end of the list as well as at the beginning.

Demonstration on Double-Ended Linked List:

/**
 *
 */

/**
 * @author Abhinaw.Tripathi
 *
 */
class Link
{
 public long dData;
 public Link next;

 public Link(long d)
 {
this.dData=d;
 }

 public void displayLink()
 {
 System.out.println(dData+ " ");
 }

}

class FirstLastList
{
private Link first;
private Link last;

public FirstLastList()
{
first=null;
last=null;
}

public boolean isEmpty()
{
return first== null;
}

public void insertFirst(long dd)
{
Link newLink=new Link(dd);
if(isEmpty())
first=newLink;

else
last=newLink;
last=newLink;
}


public void insertLast(long dd)
{
Link newLink=new Link(dd);
if(isEmpty())
first=newLink;
else
last.next =newLink;
last=newLink;
}

public long deleteFirst()
{
long temp=first.dData;
if(first.next == null)
last=null;
first=first.next;

return temp;
}

public void displayList()
{
 System.out.println("First----->Last : ");
 Link current=first;
 while(current!=null)
 {
 current.displayLink();
 current=current.next;
 }
 System.out.println(" ");
}

}

public class DoubleEndedTestApp {

public static void main(String[] args) {

FirstLastList theList=new FirstLastList();
theList.insertFirst(22);
theList.insertFirst(44);
theList.insertFirst(66);
theList.insertLast(11);
theList.insertLast(33);

theList.displayList();
theList.deleteFirst();
theList.displayList();
}


}