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 statement

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.

Java program to check whether a queue is empty or not

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.