Linked List implementation in Java

Before creating the linked list first we need to create  individual links this can be achieved with the help of a special class called as Self referential class Link

class Link

{

    public int rollNo;

    public String name;

    public Link next;

    public Link(int rNo,String n)

    {

        rollNo=rNo;

        name=n;

    }

    public void displayLink()

    {

        System.out.print("{"+rollNo+","+name+"}");

    }

}

Here the rollNo and name are the information associated with the node and next is the referential variable to hold the address of the next node in the list.

The LinkList Class

The LinkList class contains only one element called as first which is used to maintain the address of first link in the list. Since in order to process the list, it’s mandatory to know the starting address of the list. Using the first link address all the Links can be processed very easily.

Basic operations on Single Linked lists

·    Inserting an item at the beginning of the list.

·    Deleting the item at the beginning of the list.

·    Display the contents of the entire list.

class LinkList

{

                private Link first;

                public void LinkList( )

{

                                first = null;

}

public boolean isEmpty( )

{

                                return(first==null);

}

public void insertFirst( ----)

{              

                ======

}

public Link deleteFirst()

{

                =====

}

public  void displayList()

{              

                ======

}

}

Here insertFirst() - inserts a Link at the beginning of the Linked List

deleteFirst() -  removes a Link at the  beginning of the Linked List

displayList() - used to traverse to display all the Links in the LinkedList

Java program to perform basic operations of Single Linked List

class LinkList

{

    public Link first;

    public LinkList()

    {

        first=null;

    }

   public boolean isEmpty()

    {

        return (first==null);

    }

    public void insertFirst(int rNo,String n)

    {

        Link L=new Link(rNo,n);

        L.next=first;

        first=L;

    }

    public  Link deleteFirst()

    {

        Link temp=first;

        first=first.next;

        return temp;

    }

               

    public void displayList()

    {

        System.out.print("\nList:[");

        Link current=first;

        while(current!=null)

        {

          current.displayLink();

          current=current.next;

        }

        System.out.println("]");

    }

}

 

public class LinkListApp

{

    public static void main(String[] args)

    {

        LinkList  LST=new LinkList();

        //adding the elements into the LinkedList

        LST.insertFirst(17001, "Raju");

        LST.insertFirst(17002, "Divya");

        LST.insertFirst(17003, "Hari");

        LST.insertFirst(17004, "Teja");

        //Displaying the Links in the LinkedList

        LST.displayList();

        // Deleting Link from the LinkedList 

        Link temp=LST.deleteFirst();

        System.out.println("Deleted LInk :");

        temp.displayLink();

        LST.displayList();

       

    }

   

}