Queue , Deque class

Queue performs FIFO(First In First Out) Queue
Deque is Double ended Queue. we can use addFirst or addLast to DeQueue.

public class Outer {
    public static void main(String args[]) {
        Queue<Integer> q = new ArrayDeque<>();
        q.add(1);
        q.add(2);
        q.add(3);
        q.forEach(System.out::println);
    }
}

1
2
3

public class Outer {
    public static void main(String args[]) {
        Deque<Integer> q = new ArrayDeque<>();
        q.add(1);
        q.add(2);
        q.add(3);
        q.addFirst(98);
        q.addFirst(99);
        q.addLast(5);
        q.addLast(6);
        q.forEach(System.out::println);
    }
}

99
98
1
2
3
5
6