Java program to check whether a queue is empty or not

Java example to check whether a queue is empty or not.
Submitted by Nidhi, on April 27, 2022

Problem Solution:

In this program, we will create 2 queues using the Queue interface with the help of Linked List collection and store elements in a FIFO (First In First Out) manner. Then we will check whether queues are empty or not using the isEmpty() method.

Program/Source Code:

The source code to check whether a queue is empty or not is given below. The given program is compiled and executed successfully.

// Java program to check a queue is empty or not

import java.util.LinkedList;
import java.util.Queue;

public class Main {
  public static void main(String[] args) {
    Queue < Integer > queue = new LinkedList < > ();
    Queue < Integer > emQueue = new LinkedList < > ();

    queue.add(10);
    queue.add(20);
    queue.add(30);
    queue.add(40);
    queue.add(50);

    if (queue.isEmpty())
      System.out.println("The queue is empty.");
    else
      System.out.println("The queue is not empty.");

    if (emQueue.isEmpty())
      System.out.println("The emQueue is empty.");
    else
      System.out.println("The emQueue is not empty.");
  }
}

Output:

The queue is not empty.
The emQueue is empty.

Explanation:

In the above program, we imported the "java.util.LinkedList" and "java.util.Queue" packages to use the Queue Interface and LinkedList collection respectively. Here, we created a class Main. The Main class contains a main() method. The main() method is the entry point for the program.

In the main() method, we created 2 queues using LinkedList collection and added items to it. Then we checked whether queues are empty or not using the isEmpty() method and printed the appropriate message.