Program to create, insert, delete and display operations on double linked list?:

import java.io.*;

class node

{

public int x;

public node next;

public node prev;

}

class DoubleLinkedList

{

public node first;

public node last;

DoubleLinkedList()

{

first=new node();

first.next=null;

first.prev=null;

last=first;

}

void add (int v)

{

node temp=new node();

temp.x=v;

temp.next=null;

last.next=temp;

temp.prev=last;

last=temp;

}

void insert(int p,int v)

{

node ptr=first,temp;

for(int i=1;i<=p-1;i++)

ptr=ptr.next;

if(ptr.next==null)

add(v);

else

{

temp=new node();

temp.x=v;

temp.next=ptr.next;

ptr.next.prev=temp;

ptr.next=temp;

temp.prev=ptr;

}

}

void del(int p)

{

node ptr=first,temp;

for(int i=1;i<=p-1;i++)

ptr=ptr.next;

if(ptr.next.next==null)

{

temp=last;

last=last.prev;

last.next=null;

}

else

{

temp=ptr.next;

ptr.next=ptr.next.next;

ptr.next.prev=ptr;

}

temp=null;

}

void show()

{

System.out.println("\nList Elements:Left to Right");

for(node ptr=first.next;ptr!=null;ptr=ptr.next)

System.out.print("\t"+ptr.x);

System.out.println("\nList Elements:Right to Left");

for(node ptr=last;ptr.prev!=null;ptr=ptr.prev)

System.out.print("\t"+ptr.x);

}

}

Class DListTest

{

public static void main(String as[]) throws Exception

{

String con="";

int x,op,p,v;

DoubleLinkedList l1=new DoubleLinkedList();

InputStreamReader isr=new InputStreamReader(System.in);

BufferedReader br=new BufferedReader(isr);

System.out.println("Enter elements to create");

do

{

x=Integer.parseInt(br.readLine());

l1.add(x);

System.out.print("Add more?(y,n):");

con=br.readLine();

}while(con.equals("y"));

l1.show();

do

{

System.out.println("\n 1.Insert\n 2.Delete \n 3.Display \n 4.Exit");

System.out.println("\nSelect an option:");

op=Integer.parseInt(br.readLine());

if(op==1)

{

System.out.println("Enter Position to insert:");

p= Integer.parseInt(br.readLine());

System.out.println("Enter Value to insert:");

v= Integer.parseInt(br.readLine());

l1.insert(p,v);

}

if(op==2)

{

System.out.println("Enter Position to delete:");

p= Integer.parseInt(br.readLine());

l1.del(p);

}

l1.show();

}while(op<4);

}

}

/* Output: */

Enter elements to create

30

Add more?(y,n):y

40

Add more?(y,n):y

50

Add more?(y,n):n

List Elements:Left to Right

30 40 50

List Elements:Right to Left

50 40 30

1.Insert

2.Delete

3.Display

4.Exit

Select an option:1

Enter Position to insert:2

Enter Value to insert:99

List Elements:Left to Right

30 99 40 50

List Elements:Right to Left

50 40 99 30

1.Insert

2.Delete

3.Display

4.Exit

Select an option: 4