ArrayBlockingQueue size() Method in Java

Last Updated : 11 Jul, 2025

ArrayBlockingQueue is bounded, blocking queue that stores the elements internally backed by an array.

ArrayBlockingQueue class is a member of the Java Collections Framework.
Bounded means it will have a fixed size, you can not store number the elements more than the capacity of the queue.
The queue also follows FIFO (first-in-first-out) rule for storing and removing elements from the queue.
If you try to put an element into a full queue or to take an element from an empty queue then the queue will block you.

The size() method returns the number of elements that queue contains. Size is an important method to see how many elements the queue contains and how many elements can be added to this queue by calculating the difference between the capacity of queue and size of the queue.
Syntax:

public int size()

Parameters: The method does not take any parameters.
Return Value:The method returns the number of elements in this queue.
Below programs illustrate size() method of ArrayBlockingQueue.
Program 1:

Java

// Program to Demonstrate the size() method
// of ArrayBlockingQueue.

import java.util.concurrent.ArrayBlockingQueue;

public class GFG {

public static void main(String[] args) {
    // Define capacity of ArrayBlockingQueue
    int capacity = 5;
    
    // Create object of ArrayBlockingQueue
    ArrayBlockingQueue<Integer> queue = new 
                 ArrayBlockingQueue<Integer>(capacity);
    
    // Add elements to ArrayBlockingQueue
    queue.add(23);
    queue.add(32);
    queue.add(45);
    
    // Print size of queue after adding numbers
    int size=queue.size();
    System.out.println("After adding numbers"+
                              " Queue size = " +size);
    
    // Add more elements to ArrayBlockingQueue
    queue.add(88);
    queue.add(42);
    
    // Print size of queue after adding numbers
    size=queue.size();
    System.out.println("After adding more numbers"
                               +" Queue size = " +size);
    
} 
}

Program 2:

Java

// Program to demonstrate size() method of
// ArrayBlockingQueue.

import java.util.concurrent.ArrayBlockingQueue;

public class GFG {

public static void main(String[] args) {
// Define capacity of ArrayBlockingQueue
    int capacity = 5;
     
    // Create object to store 5 names
    ArrayBlockingQueue<String> names = new 
             ArrayBlockingQueue<String>(capacity);
     
    // Add element to ArrayBlockingQueue
    names.add("Aman");
    names.add("Siddhant");
   
    
    // Print size of queue after adding numbers
    int size = names.size();
    System.out.println("After adding numbers"+
                            " Queue size = "+size);
    
    
    // Add more elements to ArrayBlockingQueue
    names.add("Raunak");
    names.add("Suvo");
    
    // Print size of queue after adding numbers
    size=names.size();
    System.out.println("After adding more numbers"+
                                 " Queue size = "+size);
    
} 
}