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Java Program to Implement LinkedList
In this article, we will understand how to implement linked-list. The java.util.LinkedList class operations perform we can expect for a doubly-linked list. Operations that index into the list will traverse the list from the beginning or the end, whichever is closer to the specified index.
Below is a demonstration of the same −
Suppose our input is −
Run the program
The desired output would be −
The elements of the linked list are: 100 150 200 250
Algorithm
Step 1 - START Step 2 - Create a class with the required members. Step 3 - Define an ‘insert’ function to add elements to the list. Step 4 - In the ‘main’ method, create a new instance of the class. Step 5 - Create a list, and add elements to it using the ‘insert’ method. Step 6 - Iterate over the list, and display the value present in the current node. Step 7 - Move on to the next node and perform the same operation. Step 8 - Do this until the end of the list is reached. Step 9 - Display the result Step 10 - Stop
Example 1
Here, we bind all the operations together under the ‘main’ function.
public class Demo {
Node head;
static class Node {
int data;
Node next_element;
Node(int element){
data = element;
next_element = null;
}
}
public static Demo insert(Demo input_list, int data){
Node new_node = new Node(data);
new_node.next_element = null;
if (input_list.head == null) {
input_list.head = new_node;
}
else {
Node last = input_list.head;
while (last.next_element != null) {
last = last.next_element;
}
last.next_element = new_node;
}
return input_list;
}
public static void main(String[] args){
Demo input_list = new Demo();
System.out.print("A linked list is declared: \n");
input_list = insert(input_list, 100);
input_list = insert(input_list, 150);
input_list = insert(input_list, 200);
input_list = insert(input_list, 250);
Node current_node = input_list.head;
System.out.print("The elements of the linked list are: \n");
while (current_node != null) {
System.out.print(current_node.data + " ");
current_node = current_node.next_element;
}
}
}Output
A linked list is declared: The elements of the linked list are: 100 150 200 250
Example 2
Here, we encapsulate the operations into functions exhibiting object oriented programming.
public class Demo {
Node head;
static class Node {
int data;
Node next_element;
Node(int element){
data = element;
next_element = null;
}
}
public static Demo insert(Demo input_list, int data){
Node new_node = new Node(data);
new_node.next_element = null;
if (input_list.head == null) {
input_list.head = new_node;
}
else {
Node last = input_list.head;
while (last.next_element != null) {
last = last.next_element;
}
last.next_element = new_node;
}
return input_list;
}
public static void print_list(Demo input_list){
Node current_node = input_list.head;
System.out.print("The elements of the linked list are: \n");
while (current_node != null) {
System.out.print(current_node.data + " ");
current_node = current_node.next_element;
}
}
public static void main(String[] args){
Demo input_list = new Demo();
System.out.print("A linked list is declared: \n");
input_list = insert(input_list, 100);
input_list = insert(input_list, 150);
input_list = insert(input_list, 200);
input_list = insert(input_list, 250);
print_list(input_list);
}
}Output
A linked list is declared: The elements of the linked list are: 100 150 200 250
Updated on: 30-Mar-2022
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