Java Program to Find the Max and Min Values in a Linked List

In this article we are going to see how we can find the max and min values in a linked list by using Java programming language.

Java Program to Find the Max and Min Values in a Linked List

Approach:

• Create a linked list.
• Add elements to the list.
• Display the elements.
• Call the user defined method minVal() and maxVal() method to find the min and max value from the list. The method stores the head element in variable and compares it with the data from the rest of the list and prints the min/max value.

Program:

import java.util.*;
// Main class
public class Main
{
    // Class Node that defines the two linked list variables
    class Node
    {
        int data;
        Node nextNode;
        // constructor to create a node
        public Node(int data) 
        {    
            this.data = data;    
            this.nextNode = null;    
        }    
    }

    // Setting the head and end of the node as NULL  
    public Node head = null;    
    public Node tail = null;  

    // method to find the minimum value in the linked list  
    public void minVal() 
    {  
        Node curr = head;  
        int min;  
        if(head == null)
        {  
            System.out.println("Linked list is empty");  
        }  
        else 
        {  
            //Store the first node data
            min = head.data;  
            while(curr != null)
            {  
                //compare min with each node and if any value is smaller than min replace min with it.
                if(min > curr.data) 
                {  
                    min = curr.data;  
                }  
                curr= curr.nextNode;  
            }  
            System.out.println("Minimum value in the list is "+ min);  
        }  
    }  

    // method to find the maximum value in the linked list  
    public void maxVal() 
    {  
        Node curr = head;  
        int max;  
        if(head == null) 
        {  
            System.out.println("Linked list is empty");  
        }  
        else 
        {  
            //Storing the first node data in max  
            max = head.data;  
            while(curr != null)
            {  
                //compare max with each node and if any value is bigger than max replace min with it.  
                if(max < curr.data) 
                {  
                    max = curr.data;  
                }  
                curr = curr.nextNode;  
            }  
            System.out.println("Maximum value in the list is "+ max);  
        }  
    }  

    // method to add a node to the end of the linked list
    public void add(int data)
    {
        Node newNode = new Node(data);
        // Checks if there was any previous node
        if(head==null)
        {
            head = newNode;
            tail = newNode;
        }
        else
        {
            tail.nextNode = newNode;
            tail = newNode;
        }
    }
    
    // Method to display all the nodes of the linked list
    public void show()
    {
        Node curr = head;
        // If the head is pointing to no node then the linked list is empty
        if(head==null)
            System.out.println("Linked List is empty");
        else
        {
            System.out.println("The nodes are:");
            while(curr!=null)
            {
                System.out.print(curr.data+",");
                curr = curr.nextNode;
            }
            System.out.println();
        }
    }

    public static void main(String[] args) 
    {
        // create an object of the main class
        Main ll = new Main();
        // add elements to the linked list
        ll.add(10);
        ll.add(20);
        ll.add(30);
        ll.add(40);
        ll.add(50);
        // display the nodes
        ll.show();
        ll.minVal();
        ll.maxVal();
    }
}

Output:

The nodes are:
10,20,30,40,50,
Minimum value in the list is 10
Maximum value in the list is 50

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