A linked list is made up of a series of objects, called the nodes of the list. Because a list node is a distinct object. Linked lists are among the simplest and most common data structures.
The principal benefit of a linked list over a conventional array is that the list elements can easily be inserted or removed without reallocation or reorganization of the entire structure because the data items need not be stored contiguously in memory or on disk, while an array has to be declared in the source code, before compiling and running the program. Linked lists allow insertion and removal of nodes at any point in the list, and can do so with a constant number of operations if the link previous to the link being added or removed is maintained during list traversal.

Singly Linked List:
Singly linked lists contain nodes which have a data field as well as a next field, which points to the next node in line of nodes. Operations that can be performed on singly linked lists include insertion, deletion and traversal.

Finding and Deleting Specified Link:
Finding algorithm
Beginning from the head, 1. Check, if the end of a list hasn't been reached yet; 2. Do some actions with the current node, which is specific for particular algorithm; 3. Current node becomes previous and next node becomes current.
Deleting
4. Save reference to link 5. Delete it, save first to old next 6. Return deleted link
Operation on Singly Link List: * Search * Insert * Delete
Doubly Linked List
Different from a singly linked list, a doubly linked list allows us to go in both directions -- forward and reverse. Such lists allow for a great variety of quick update operations, including insertion and removal at both ends, and in the middle. A node in a doubly linked list stores two references -- a next link, which points to the next node in the list, and a prev link, which points to the previous node in the list.

Operation on Doubly Link List: * Search * Insert * Delete

Sample Program of Singly Linked List

import java.io.*; import java.util.Scanner; class linkedlist { int data; linkedlist next; linkedlist(int value) { this.data = value; } void display() { System.out.println(data); } } class linked { public linkedlist fstnode, lastnode; linked() { fstnode = null; lastnode = null; } /* Insert node or create linked list */ void insertnode(int value) { linkedlist node = new linkedlist(value); node.next = null; if(fstnode == null) { fstnode = lastnode = node; System.out.println("Linked list created successfully!"); } else { lastnode.next = node; lastnode = node; System.out.println("Node inserted successfully!"); } } /* Delete node from linked list */ void delete() { int count = 0, number, i; linkedlist node, node1; Scanner input = new Scanner(System.in); for(node = fstnode; node != null; node = node.next) count++; display(); node = node1 = fstnode; System.out.println(count+" nodes available here!"); System.out.println("Enter the node number which you want to delete:"); number = Integer.parseInt(input.nextLine()); if(number != 1) { if(number <= count) { for(i = 2; i <= number; i++) node = node.next; for(i = 2; i <= number-1; i++) node1 = node1.next; node1.next = node.next; node.next = null; node = null; } else System.out.println("Invalid node number!\n"); } else { fstnode = node.next; node = null; } System.out.println("Node has been deleted successfully!\n"); } /* Display linked list */ void display() { linkedlist node = fstnode; System.out.println("List of node:"); while(node != null) { node.display(); node = node.next; } } }

class singlylinkedlist { public static void main(String args[ ]) { linked list = new linked(); Scanner input = new Scanner(System.in); int op = 0; while(op != 4) { System.out.println("Please select one of the ff options:”); System.out.println (“1. Insert 2. Delete 3. Display 4. Exit"); System.out.println("Enter your choice:"); op = Integer.parseInt(input.nextLine()); switch(op) { case 1: System.out.println("Enter the position value for Linked list:"); list.insertnode(Integer.parseInt(input.nextLine())); break; case 2: list.delete(); break; case 3: list.display(); break; case 4: System.out.println("Bye Bye!"); System.exit(0); break; default: System.out.println("Invalid choice!"); } } } }

Output
Please select one of the ff options:

1. Insert 2. Delete 3. Display 4. Exit
1
4
Linked list created successfully!

Please select one of the ff options:
1. Insert 2. Delete 3. Display 4. Exit
1
5
Node inserted successfully!

Please select one of the ff options:
1. Insert 2. Delete 3. Display 4. Exit
1
6
Node inserted successfully!

Please select one of the ff options:
1. Insert 2. Delete 3. Display 4. Exit
1
7
Node inserted successfully!

Please select one of the ff options:
1. Insert 2. Delete 3. Display 4. Exit
3

List of node:
4
5
6
7

Please select one of the ff options:
1. Insert 2. Delete 3. Display 4. Exit
2
List of node:
4
5
6
7
4 nodes available here!
Enter the position value of Linked list to delete:
3
Node has been deleted successfully!