JAVA

how to use deque as queue in java?

/*
	This implementation shows how to use a Deque
	object as a stack and then how to use it
	as a queue.

	Time complexity of methods used: O(1)
*/
import java.util.Deque;
import java.util.ArrayDeque;
public class DequeDemo {
	public static void main(String[] args) {
		Deque<Integer> deque = new ArrayDeque<>();
		// Deque as stack
		deque.push(4); // Insert a new top element
		deque.push(3);
		// Pop top element from stack
		System.out.println(deque.getFirst()); // 3
		deque.pop();
		System.out.println(deque.pop()); // 4

		// Deque as Queue
		deque.add(5); // Enqueue an element
		deque.add(2);
		System.out.println(deque.getFirst()); // 5
		// Dequeue the front element of queue
   		deque.removeFirst();
		System.out.println(deque.removeFirst()); // 2
	}
}

Java How to use Queue?

// LinkedList implementation of Queue
Queue<String> animal1 = new LinkedList<>();

// Array implementation of Queue
Queue<String> animal2 = new ArrayDeque<>();

// Priority Queue implementation of Queue
Queue<String> animal 3 = new PriorityQueue<>();

dequeue element to queue java

Queue<String> queue = new LinkedList<>();

queue.add("element 1");
queue.add("element 2");

String element1 = queue.poll();

String element2 = queue.remove();