Introduction to doubly linked list

//Introduction to doubly linked list

import java.io.*;
import java.util.*;

class Node {
    int data;
    Node next;
    Node prev;

    Node(int x) {
        data = x;
        next = null;
        prev= null;
    }
}

class GFG {
    public static void main(String args[]) throws IOException {
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();

        while(t-- > 0) {
            int n = sc.nextInt();
            int[] arr =new int[n];

            for(int i = 0; i < n; i++)
                arr[i] = sc.nextInt();

            Solution obj = new Solution();
            Node ans = obj.constructDLL(arr);

            while(ans != null) {
                System.out.print(ans.data + " ");
                ans = ans.next;
            }
            System.out.println();
        }
    }
}

class Solution {
    Node constructDLL(int arr[]) {
        Node head = new Node(arr[0]);
        Node temp = head;
        
        for(int i = 1; i < arr.length; i++) {
            Node newNode = new Node(arr[i]);
            newNode.next = null;
            newNode.prev = temp;
            temp.next = newNode;
            temp = newNode;
        }
        
        return head;
    }
}