Doubly Linked list
by Geekboots | Java Programming | Mon, 06 Jun 2016
import java.io.*;
import java.util.Scanner;
class linkedlist {
int data;
linkedlist prev;
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 at the beginning or create linked list */
void insert_front(int value) {
linkedlist node = new linkedlist(value);
if(fstnode == null) {
node.prev = node.next = null;
fstnode = lastnode = node;
System.out.println("Lined list created successfully!");
}
else {
node.prev = null;
node.next = fstnode;
fstnode.prev = node;
fstnode = node;
System.out.println("Node Inserted at the front of the Linked list!");
}
}
/* Insert node at the end or create linked list */
void insert_end(int value) {
linkedlist node = new linkedlist(value);
if(fstnode == null) {
node.prev = node.next = null;
fstnode = lastnode = node;
System.out.println("Lined list created successfully!");
}
else {
node.next = null;
node.prev = lastnode;
lastnode.next = node;
lastnode = node;
System.out.println("Node Inserted at the end of the Linked list!");
}
}
/* Delete node from linked list */
void delete() {
int count = 0, number, i;
linkedlist node, node1, node2;
Scanner input = new Scanner(System.in);
for(node = fstnode; node != null; node = node.next)
count++;
display();
node = node1 = node2 = fstnode;
System.out.println(count+" nodes available here!");
System.out.println("Enter the node number which you want to delete from ascending order list:");
number = Integer.parseInt(input.nextLine());
if(number != 1) {
if(number < count && number > 0) {
for(i = 2; i <= number; i++)
node = node.next;
for(i = 2; i <= number-1; i++)
node1 = node1.next;
for(i = 2; i <= number+1; i++)
node2 = node2.next;
node2.prev = node1;
node1.next = node2;
node.prev = null;
node.next = null;
node = null;
}
else if(number == count) {
node = lastnode;
lastnode = node.prev;
lastnode.next = null;
node = null;
}
else
System.out.println("Invalid node number!\n");
}
else {
node = fstnode;
fstnode = node.next;
fstnode.prev = null;
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 in Ascending order!");
while(node != null) {
node.display();
node = node.next;
}
node = lastnode;
System.out.println("List of node in Descending order!");
while(node != null) {
node.display();
node = node.prev;
}
}
}
class doublylinkedlist {
public static void main(String args[ ]) {
linked list = new linked();
Scanner input = new Scanner(System.in);
int op = 0;
while(op != 5) {
System.out.println("1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit");
System.out.println("Enter your choice:");
op = Integer.parseInt(input.nextLine());
switch(op) {
case 1:
System.out.println("Enter the positive value for Linked list:");
list.insert_front(Integer.parseInt(input.nextLine()));
break;
case 2:
System.out.println("Enter the positive value for Linked list:");
list.insert_end(Integer.parseInt(input.nextLine()));
break;
case 3:
list.delete();
break;
case 4:
list.display();
break;
case 5:
System.out.println("Bye Bye!");
System.exit(0);
break;
default:
System.out.println("Invalid choice!");
}
}
}
}
/****** Output ******/
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
1
Enter the positive value for Linked list:
4
Linked list created successfully!
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
1
Enter the positive value for Linked list:
5
Node inserted successfully!
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
1
Enter the positive value for Linked list:
6
Node inserted successfully!
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
2
Enter the positive value for Linked list:
7
Node inserted successfully!
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
2
Enter the positive value for Linked list:
8
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
4
List of node in Ascending order!
6
5
4
7
8
List of node in Descending order!
8
7
4
5
6
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
3
List of node in Ascending order!
6
5
4
7
8
List of node in Descending order!
8
7
4
5
6
5 nodes available here!
Enter the node number which you want to delete from ascending order list:
3
Node has been deleted successfully!
1. Insert at front 2. Insert at back 3. Delete 4. Display 5. Exit
Enter your choice:
5
Bye Bye!