Airbnb-QueueLinkedList-2/3, Java

Airbnb-QueueLinkedList-2/3

//'main' method must be in a class 'Rextester'.
//Compiler version 1.8.0_111

import java.util.*;
import java.lang.*;

class Rextester
{  
    public static class QueueWithFixedArray {
        private int fixedSize;

private int count;
        private int head;
        private int tail;
        private List<Object> headList;
        private List<Object> tailList;

public QueueWithFixedArray(int fixedSize) {
            this.fixedSize = fixedSize;
            this.count = 0;
            this.head = 0;
            this.tail = 0;
            this.headList = new ArrayList<>();
            this.tailList = this.headList;
        }

public void offer(int num) {
            if (tail == fixedSize - 1) {
                List<Object> newList = new ArrayList<>();
                newList.add(num);
                tailList.add(newList);
                tailList = (List<Object>) tailList.get(tail);
                tail = 0;
            } else {
                tailList.add(num);
            }
            count++;
            tail++;
        }

public Integer poll() {
            if (count == 0) {
                return null;
            }

int num = (int) headList.get(head);
            head++;
            count--;

if (head == fixedSize - 1) {
                List<Object> newList = (List<Object>) headList.get(head);
                headList.clear();
                headList = newList;
                head = 0;
            }

return num;
        }

public int size() {
            return count;
        }
    }
    
    public static void main(String args[])
    {
        QueueWithFixedArray queue = new QueueWithFixedArray(3);
        queue.offer(1);
        queue.offer(2);
        queue.offer(3);
        queue.offer(4);
        queue.offer(5);
        
        System.out.println(queue.poll());
        System.out.println(queue.poll());
        System.out.println(queue.poll());
        System.out.println(queue.poll());
        System.out.println(queue.poll());
        System.out.println(queue.poll());
        
    }
}


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