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Here is how to create linked list in java.A linked list is a linear data structure.
Linked List in Java
A linked list is a linear data structure. Linked List is
collection of nodes; nodes are containers having at least two parts: one for
storing data and another for storing address of another node. Linked List is
very flexible kind of data structure; insertion and deletion of any node from
any position is possible, but random access of the nodes is not possible in the
linked list.
The elements in a linked list are linked using
pointers as shown in the below image:
fig:
Linked List
Types:
·SinglyLinked List
·Doubly Linked List
·Circular Linked List
·Doubly Circular Linked List
Singly
Linked List:
It
is the simplest type of linked list in which every node contains some data and
a pointer to the next node of the same data type. The node contains a pointer to
the next node means that the node stores the address of the next node in the
sequence. A single linked list allows traversal of data only in one way.
Creation
of Singly Linked List node in java:
Class SLLNode{
int info;
SLLNode next;
}
Source Code:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package LinkedList;
import java.util.*;
/**
*
* @author AnkeetPC
*/
// inserting and deleting first and last node of SLL
class SLLNode{
int info; //data holder
SLLNode next; // address holder
}
class SLL{
SLLNode first,last;
public void insertAtFirst(int data){
SLLNode newnode = new SLLNode();
newnode.info = data;
if(first == null){
newnode.next = null;
first = newnode;
last = newnode;
}else{
newnode.next = first;
first = newnode;
}
}
public void insertAtEnd(int data){
SLLNode newnode = new SLLNode();
newnode.info = data;
if(first == null){
newnode.next = null;
first = newnode;
last = newnode;
}else{
last.next = newnode;
last = newnode;
}
}
public void deleteAtFirst(){
SLLNode temp = first;
if(first == null){
System.out.println("Empty List");
}else{
first = first.next;
temp.next = null;
}
}
public void deleteAtLast(){
SLLNode temp = first;
if(first == null){
System.out.println("EmptyList");
}else if(first == last){
first = null;
last = null;
}else{
while(temp.next!=last){
temp = temp.next;
}
temp.next= null;
last = temp;
}
}
public void insertAtSpecifiedPos(int data){
int position;
SLLNode newnode = new SLLNode();
SLLNode temp = new SLLNode();
newnode.info = data;
System.out.println("Enter the position: ");
Scanner input = new Scanner(System.in);
position = input.nextInt();
if(first == null){
newnode.next = null;
first = newnode;
last = newnode;
}else{
temp = first;
for(int i=0;i<position-1;i++){
temp =temp.next;
}
newnode.next = temp.next;
temp.next = newnode;
}
}
public void search(int data){
SLLNode temp = first;
int flag = 0;
while(temp!=null){
if(temp.info==data){
flag =1;
System.out.println("Data found: "+temp.info);
}
temp = temp.next;
}
if(flag ==0){
System.out.println("Not found");
}
}
public void display(){
SLLNode temp = first;
if(first == null){
System.out.println("Empty list");
}else{
while(temp.next!=null){
System.out.println(temp.info+"");
temp = temp.next;
}
System.out.println(temp.info+"");
}
}
}
public class SLLDemo {
public static void main(String[] args) {
SLL ob = new SLL();
ob.insertAtFirst(15);
ob.insertAtFirst(20);
ob.insertAtFirst(25);
ob.insertAtEnd(55);
ob.insertAtEnd(35);
ob.insertAtEnd(88);
ob.deleteAtFirst();
ob.deleteAtLast();
// ob.insertAtSpecifiedPos(45);
ob.search(55);
ob.display();
}
}
Doubly
Linked List:
A
doubly linked list or a two-way linked list is a more complex type of linked
list which contains a pointer to the next as well as the previous node in
sequence, Therefore, it contains three parts are data, a pointer to the next
node, and a pointer to the previous node. This would enable us to traverse the
list in the backward direction as well.
Creation
of Doubly Linked List node in java:
Class DLLNode{
int info;
DLLNode next,prev;
}
Source Code:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package LinkedList;
/**
*
* @author AnkeetPC
*/
// inserting and deleting first and last node of DLL
class DLLNode{
int info; // data holder
DLLNode next,prev; //address holder
}
class DLL{
DLLNode first, last;
public void insertAtFirst(int data){
DLLNode newnode = new DLLNode();
newnode.info = data;
if(first == null && last == null){
first = newnode;
last = newnode;
}else{
newnode.next = first;
first.prev = newnode;
first = newnode;
}
}
public void insertAtLasr(int data){
DLLNode newnode = new DLLNode();
newnode.info = data;
if(first == null && last == null){
first = newnode;
last = newnode;
}else{
last.next = newnode;
newnode.prev = last;
last = newnode;
}
}
public void deleteFirst(){
if(first == null && last == null){
System.out.println("Empty List");
}else if(first == last){
first = null;
last = null;
}else{
DLLNode temp = first;
first = first.next;
temp.next = null;
first.prev = null;
}
}
public void deleteLast(){
if(first==null && last == null){
System.out.println("Empty List");
}else if(first == last){
first = null;
last = null;
}else{
DLLNode temp=first;
while(temp.next!=last){
temp = temp.next;
}
temp.next = null;
last = temp;
}
}
public void display(){
DLLNode temp = first;
if(temp == null){
System.out.println("Empty List");
}else{
while(temp!=last.next){
System.out.println(temp.info+"");
temp = temp.next;
}
}
}
}
public class DLLDemo {
public static void main(String[] args) {
DLL ob = new DLL();
ob.insertAtFirst(15);
ob.insertAtFirst(25);
ob.insertAtFirst(45);
ob.insertAtLasr(55);
ob.deleteFirst();
ob.deleteLast();
ob.display();
}
}
Circular
Linked List:
A circular linked list
is that in which the last node contains the pointer to the first node of the
list. While traversing a circular liked list, we can begin at any node and
traverse the list in any direction forward and backward until we reach the same
node we started. Thus, a circular linked list has no beginning and no end.
Creation
of Circular Linked List node in java:
Class CLLNode{
int info;
CLLNode next;
}
Source Code:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package LinkedList;
/**
*
* @author AnkeetPC
*/
// inserting and deleting first and last node from CLL
class CLLNode{
int info; // data holder
CLLNode next; // address holder
}
class CLL{
CLLNode first,last;
public void insertFirst(int data){
CLLNode newnode = new CLLNode(); // node creation
newnode.info = data;
if(first == null){
newnode.next = null;
first = newnode;
last = newnode;
}else{
newnode.next = first;
first = newnode;
last.next = newnode;
}
}
public void insertLast(int data){
CLLNode newnode = new CLLNode(); // node creation
newnode.info = data;
if(first == null){
newnode.next = null;
first = newnode;
last = newnode;
}else{
newnode.next = last.next;
last.next = newnode;
last = newnode;
}
}
public void deleteFirst(){
if(first == null && last == null){
System.out.println("Empty List");
}else if(last == last.next){
last.next= null;
last = null;
}else{
CLLNode temp = first;
first = first.next;
last.next = first;
temp = null;
}
}
public void deleteLast(){
if(first == null && last ==null){
System.out.println("Empty List");
}else if(last == last.next){
last.next = null;
last = null;
}else{
CLLNode temp = first;
while(temp.next!= last){
temp = temp.next;
}
temp.next = first;
last = temp;
}
}
public void display(){
CLLNode temp = first;
if(first == null){
System.out.println("Empty List");
}else{
while(temp.next!=first){
System.out.println(temp.info+"");
temp = temp.next;
}
System.out.println(temp.info+"");
}
}
}
public class CLLDemo {
public static void main(String[] args) {
CLL ob = new CLL();
ob.insertFirst(25);
ob.insertFirst(77);
ob.insertLast(88);
ob.insertLast(89);
ob.deleteFirst();
ob.deleteLast();
ob.display();
}
}
Doubly
Circular Linked List:
A Doubly Circular
linked list or a circular two-way linked list is a more complex type of
linked-list that contains a pointer to the next as well as the previous node in
the sequence. The difference between the doubly linked and circular doubly list
is the same as that between a singly linked list and a circular linked list.
The circular doubly linked list does not contain null in the previous field of
the first node.
Creation
of Doubly Circular Linked List node in java:
Class DCLLNode{
int info;
DCLLNode next,prev;
}
Source Code:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package LinkedList;
/**
*
* @author AnkeetPC
*/
// inserting and deleting first and last node from DCLL
class DCLLNode{
int info; // data holder
DCLLNode prev,next; // adress holder
}
class DCLL{
DCLLNode first,last;
public void insertFirst(int data){
DCLLNode newnode = new DCLLNode(); // node creation
newnode.info = data;
if(first == null && last == null){
newnode.next =newnode;
newnode.prev = newnode;
first = newnode;
last = newnode;
}else{
newnode.next = first;
first.prev =newnode;
first = newnode;
newnode.prev= last;
first.prev = last;
}
}
public void insertLast(int data){
DCLLNode newnode = new DCLLNode(); // node creation
newnode.info = data;
if(first == null && last== null){
newnode.next = newnode;
newnode.prev = newnode;
first = newnode;
last = newnode;
}else{
last.next = newnode;
newnode.next = first;
newnode.prev = last;
first.prev = newnode;
last = newnode;
}
}
public void deleteFirst(){
if(first == null && last == null){
System.out.println("Empty List");
}else if(first == last){
first = null;
last = null;
}else{
DCLLNode temp = first;
first = first.next;
temp.next = null;
first.prev = last;
last.next= first;
}
}
public void deleteLast(){
if(first== null && last == null){
System.out.println("EMpty list");
}else if(first == last){
first = null;
last = null;
}else{
DCLLNode temp =first;
last = last.prev;
temp.prev = null;
first.prev= last;
last.next = first;
}
}
public void display(){
DCLLNode temp = first;
if(first == null){
System.out.println("Empty List");
}else{
do{
System.out.println(temp.info+"");
temp = temp.next;
}while(temp!=last);
System.out.println(temp.info+"");
}
}
}
public class DCLLDemo {
public static void main(String[] args) {
DCLL ob = new DCLL();
ob.insertFirst(88);
ob.insertFirst(101);
ob.insertLast(99);
ob.deleteFirst();
ob.deleteLast();
ob.display();
}
}
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