How to Remove Duplicate Elements From Java LinkedList?

// Java Program to Remove Duplicate Elements From LinkedList
import java.io.*;

// Creating the node class for a singly linkedlist
class Node {
    Node next;
    int data;

    public Node(int data)
    {
        this.data = data;
        this.next = null;
    }
}

public class singlyLinkedList {

    // Defining the head and tail of a singly linkedlist
    public Node head = null;
    public Node tail = null;

    // creating add() that enables addition
    // of a new node to the list
    public void add(int data)
    {
        // Creating a new node
        Node newNode = new Node(data);

        // Checking whether the list is empty or not
        if (head == null) {
            // If the list is found to be empty, both head
            // and tail are made to point to  the new node
            head = newNode;
            tail = newNode;
        }
        else {
            // newNode is added after tail in such a way
            // that next node of the tail points to newNode
            tail.next = newNode;
            // newNode becomes the new tail of the list
            tail = newNode;
        }
    }

    // Creating removeDuplicates() to remove
    // duplicates from the linkedlist
    public void removeDuplicates()
    {
        // current node points to the head element
        Node current = head, index = null, temp = null;

        if (head == null) {
            return;
        }
        else {
            while (current != null) {
                // temp node points to the previous node
                temp = current;
                // index node points to node next to current
                index = current.next;

                while (index != null) {
                    // checking if node of current data is
                    // equal to index node data
                    if (current.data == index.data) {

                        // duplicate node is skipped
                        temp.next = index.next;
                    }
                    else {
                        // temp node points to the previous
                        // node of index node
                        temp = index;
                    }
                    index = index.next;
                }
                current = current.next;
            }
        }
    }

    // creating print() to print all the data
    // of nodes present in the list
    public void print()
    {
        // Node current will point to head
        Node current = head;
        if (head == null) {
            System.out.println(
                "Empty list please insert some elements first");
            return;
        }
        while (current != null) {

            System.out.print(current.data + " ");
            // incrementing pointer
            current = current.next;
        }
        System.out.println();
    }

    public static void main(String[] args)
    {

        singlyLinkedList List = new singlyLinkedList();

        // Adding data to the list
        List.add(9);
        List.add(1);
        List.add(1);
        List.add(3);
        List.add(4);
        List.add(8);
        List.add(2);
        List.add(1);

        System.out.println("Initial composition : ");
        List.print();

        // removing duplicate nodes
        List.removeDuplicates();

        System.out.println("After removing duplicates : ");
        List.print();
    }
}