Question

Assume that a singly linked list is implemented with a header node, but no tail node, and that it maintains only a pointer to the header node. Write a class that includes methods to
a. return the size of the linked list
b. print the linked list
c. test if a value x is contained in the linked list
d. add a value x if it is not already contained in the linked list
e. remove a value x if it is contained in the linked list

Answer 1

All the methods are testes using switch case

Source Code

import java.util.*;
public class SinglyLinkedList {    
    class Node{    
        int data;    
        Node next;    
            
        public Node(int data) {    
            this.data = data;    
            this.next = null;    
        }    
    }    
     
    public Node head = null;    
   
    public int size() {       
        Node current = head;    
        int c=0;
        if(head == null) {    
                
            return 0;    
        }    
           
        while(current != null) {     
            c++;  
            current = current.next;    
        }    
        return c;  
    }    
    public void print() {    
        Node current = head;    
        if(head == null) {    
            System.out.println("List is empty");    
            return;    
        }    
           
        System.out.println("Nodes of singly linked list: ");    
        while(current != null) {    
            System.out.print(current.data + " ");    
            current = current.next;    
        }    
        System.out.println();    
    }    
    public int test(int x) {       
        Node current = head;    
        int f=0;
        
            while(current != null) {      
                if(current.data==x)
                    f=1;
                current = current.next;    
            }    
        
        return f;
    } 
    public void addtest(int x) {    
            Node newNode = new Node(x); 
            if(test(x)==0)
            {
                if(head==null)
                {
                    
                    head = newNode;
                    
                }
                
                Node last = head;  
                while (last.next != null) 
                    last = last.next; 
                last.next = newNode; 
                newNode.next=null;
            }
            else
            {
                System.out.println("Already present");
            }
    } 
    public void deleteNode(int key)
    {
        Node temp = head, prev = null;
        if (temp != null && temp.data == key)
        {
            head = temp.next;
            return;
        }
        while (temp != null && temp.data != key)
        {
            prev = temp;
            temp = temp.next;
        }    
        if (temp == null) 
            return;
        prev.next = temp.next;
    }
    public static void main() {    
            
        SinglyLinkedList sl = new SinglyLinkedList();    
        Scanner sc=new Scanner(System.in);   
        while(true)
        {
            System.out.println("Enter 1 to return size of linked list\nEnter 2 to print the linked list\nEnter 3 to test if value x is contained in linked list\nEnter 4 to add a value x if it is not already contained in linked list\nEnter 5 to remove a value x if it is contained in the list");
            System.out.println("Enter 0 to exit");
            System.out.println("Enter your choice");
            int ch=sc.nextInt();
            switch(ch)
            {
             case 0:System.exit(0);
             case 1:System.out.println(sl.size());break;
             case 2:sl.print();break;
             case 3:System.out.println("Enter value to test");
                    int x=sc.nextInt();
                    int f=sl.test(x);
                    if(f==1)
                       System.out.println("Value "+ x +" is contained in the linked list");
                    else
                        System.out.println("Value is not contained in the linked list");
                    break;
             case 4:System.out.println("Enter value to add");
                    int a=sc.nextInt();
                    sl.addtest(a);break;
             case 5:System.out.println("Enter value to remove");
                    int b=sc.nextInt();
                    sl.deleteNode(b);break;
             default:System.out.println("Wrong Input");break;
            }
        }
    }    
}    

Output

Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
1
0
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
2
List is empty
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
4
Enter value to add
1
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
1
1
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
2
Nodes of singly linked list: 
1 
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
4
Enter value to add
2
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
2
Nodes of singly linked list: 
1 2 
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
1
2
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
3
Enter value to test
1
Value 1 is contained in the linked list
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
3
Enter value to test
3
Value is not contained in the linked list
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
3
Enter value to test
2
Value 2 is contained in the linked list
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
5
Enter value to remove
2
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
2
Nodes of singly linked list: 
1 
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
1
1
Enter 1 to return size of linked list
Enter 2 to print the linked list
Enter 3 to test if value x is contained in linked list
Enter 4 to add a value x if it is not already contained in linked list
Enter 5 to remove a value x if it is contained in the list
Enter 0 to exit
Enter your choice
0