Question

JAVA: BASIC LINKED LISTS : Could you, please, provide SIMPLE code snippets to represent these operations?

1. Removing a data element at an index "i"

2. Removing a given data element from the end of a linked list

3. Get/find the data element at a given index

Answer 1

If you have any doubts please comment

import java.io.*;
import java.util.*;
public class LinkedList {
  
Node head;
static class Node {
int data;
Node next;
Node(int d)
{
data = d;
next = null;
}
}

//method to insert values into linkedlist
public static LinkedList insert(LinkedList list, int data)
{
Node new_node = new Node(data);
new_node.next = null;
if (list.head == null) {
list.head = new_node;
}
else {
Node last = list.head;
while (last.next != null) {
last = last.next;
}
last.next = new_node;
}
return list;
}

//method to print the linkedlist
public static void printList(LinkedList list)
{
Node currNode = list.head;
while (currNode != null) {
System.out.print(currNode.data + " ");
currNode = currNode.next;
}
}

//method to delete the element at given index
public static LinkedList deleteAtPosition(LinkedList list, int index)
{
Node currNode = list.head, prev = null;
if (index == 0 && currNode != null) {
list.head = currNode.next;
System.out.println(index + " position element deleted");
return list;
}
int counter = 0;
while (currNode != null) {
  
if (counter == index) {
prev.next = currNode.next;
System.out.println(index + " position element deleted");
break;
}
else {
prev = currNode;
currNode = currNode.next;
counter++;
}
}
if (currNode == null) {
System.out.println(index + " position element not found");
}
return list;
}

//method to delete element at end of the linkedlist
   public static LinkedList deleteAtEnd(LinkedList list)
{
Node currNode = list.head, prev = null;
       Node temp = currNode;
if (currNode == null) {
System.out.println("List is empty");
return null;
}
       if(currNode.next == null){
           currNode = null;
           return null;
       }
       else{
           while (temp.next != null) {
                   temp = temp.next;
           }
           temp = null;
       }
       return list;
}

//method to find the element at given index
   public static LinkedList findElement(LinkedList list,int index)
{
Node currNode = list.head, prev = null;
if (index == 0 && currNode != null) {
System.out.println("Data element at the given index is:" +currNode.data);
}
int counter = 0;
while (currNode != null) {
  
if (counter == index) {
System.out.println("Data element at the given index is:"+currNode.data);
break;
}
else {
prev = currNode;
currNode = currNode.next;
counter++;
}
}
if (currNode == null) {
System.out.println(index + " position element not found");
}
return list;
}

//Driver code
public static void main(String[] args)
{
LinkedList list = new LinkedList();
list = insert(list, 1);
list = insert(list, 2);
list = insert(list, 3);
list = insert(list, 4);
list = insert(list, 5);
list = insert(list, 6);
list = insert(list, 7);
list = insert(list, 8);
       int i,f;
       System.out.println("The Linked List is:");
       printList(list);
       System.out.println();
       System.out.println("Enter an index:");
       Scanner s= new Scanner(System.in);
       i=s.nextInt();
       deleteAtPosition(list,i);
       System.out.println("LinkedList after removing data element at given index is:");
       System.out.println();
       printList(list);
       deleteAtEnd(list);
       System.out.println();
       System.out.println("The last Element Removed");
       System.out.println();
       System.out.println("Enter an index to find the element:");
       f= s.nextInt();
       findElement(list,f);
}
}

Output:-