Implementing Deque with LL

arrayDeque.java

import java.util.Arrays;

class ListNode {
    int val;
    ListNode left;
    ListNode right;

    ListNode(int element) {
        val = element;
        left = null;
        right = null;
    }

}
class ArrayDeque2 {
    ListNode head;
    ListNode tail;
    int size;
    ArrayDeque2() {
        head = new ListNode(Integer.MAX_VALUE);
        tail = new ListNode(Integer.MAX_VALUE);

        head.right = tail;
        tail.left = head;
        size = 0;
    }

    void addFirst(int element) {
        ListNode oldRight = head.right;
        ListNode newNode = new ListNode(element);
        // make connection towards right proper
        head.right = newNode; newNode.left = head;
        // make connection towards left proper
        newNode.right = oldRight; oldRight.left = newNode;
        size++;
    }

    void addLast(int element) {
        ListNode oldLeft = tail.left;
        ListNode newNode = new ListNode(element);
        // make connection towards right proper
        tail.left = newNode; newNode.right = tail;
        // make connection towards left proper
        newNode.left = oldLeft; oldLeft.right = newNode;
        size++;
    }

    boolean isEmpty() {
        return head.right == tail && tail.left == head;
    }

    int removeFirst(){
        if (isEmpty()) throw new IllegalStateException();
        size--;
        int ans = head.right.val;
        head.right = head.right.right;
        head.right.left = head;
        return ans;
    }

    int peekFirst() {
        return head.right.val;
    }

    int peekLast() {
        return tail.left.val;
    }

    int removeLast() {
        if (isEmpty()) throw new IllegalStateException();
        size--;
        int ans = tail.left.val;
        tail.left = tail.left.left;
        tail.left.right = tail;
        return ans;
    }

    void print() {
        ListNode curr = head.right;
        int[] nums = new int[size];
        for (int i=0;i<size;i++) {
            nums[i] = curr.val;
            curr = curr.right;
        }
        System.out.println(Arrays.toString(nums));
    }

    int getSize() {
        return size;
    }
}
public class Main {

    public static void main(String[] args) {
        // Implementing ArrayDeque
        // 1. a size of deque
        // 2. pointers for first and last.
        // 3.
        ArrayDeque2 customDeque = new ArrayDeque2();
        customDeque.addFirst(1);
        customDeque.addLast(9);
        System.out.println(customDeque.isEmpty());
        customDeque.print();
        System.out.println(customDeque.peekLast());
        System.out.println(customDeque.peekFirst());
        customDeque.addFirst(-1);
        customDeque.addLast(99);
        customDeque.print();
        System.out.println(customDeque.removeLast());
        System.out.println(customDeque.removeLast());
        customDeque.print();
        System.out.println(customDeque.getSize());
        System.out.println(customDeque.removeLast());
        System.out.println(customDeque.removeLast());
        System.out.println(customDeque.isEmpty());
    }
}