Java ConcurrentLinkedQueue size() method

The size() method of ConcurrentLinkedQueue class returns the total count of the elements present in the queue.

Syntax:

Parameters:

Specified By:

The size() method of PriorityQueue class is specified by :

size() method in interface Collection<E>.

Return Value:

The size() method returns the total count of the elements present in this queue.

Example 1

import java.util.concurrent.ConcurrentLinkedQueue;
public class ConcurrentLinkedQueueSizeExample1 {
    public static void main(String[] args) {
        ConcurrentLinkedQueue<Integer> queue = new ConcurrentLinkedQueue<Integer>();
        queue.offer(12);
        queue.offer(67);
        queue.offer(45);
        queue.offer(123);
        //will return the total size of queue
        int a= queue.size();
        System.out.println("The size of queue : "+a);
        System.out.println("Queue : "+queue);
    }
}

Output:

The size of queue : 4
Queue : [12, 67, 45, 123]

Example 2

import java.util.*;
import java.util.concurrent.ConcurrentLinkedQueue;
class Patients{
    String Pname;
    public Patients(String pname) {
        Pname = pname;
    }
    public String toString(){
        return this.Pname;
    }
}
public class ConcurrentLinkedQueueSizeExample2 {
    static int i=1;
    public static void main(String[] args) {
    Patients patient1 = new Patients("Megha");
    Patients patient2 = new Patients("Reema");
    Patients patient3 = new Patients("Supriya");
    Patients patient4 = new Patients("Anoop");
    Patients patient5 = new Patients("Sonia");
    Patients patient6 = new Patients("Tejashvi");
        ConcurrentLinkedQueue<Patients> queue = new ConcurrentLinkedQueue<Patients>();
        List<Patients> list = new ArrayList<Patients>();
        queue.add(patient1);
        queue.add(patient2);
        queue.add(patient3);
        queue.add(patient4);
        queue.add(patient5);
        queue.add(patient6);
        // returns the total size of the queue
        System.out.println("Total Patients = "+queue.size());
        for(Patients xyz : queue){
            System.out.println(i++ +"."+xyz);
        }
        list.add(patient1);
        list.add(patient2);
        list.add(patient3);
        list.add(patient4);
        i=1;
        System.out.println("Patients recovered and discharged : "+list);
        queue.removeAll(list);
        System.out.println("Patients left in the hospital = "+queue.size());
        for (Patients xyz : queue) {
            System.out.println(i++ +"."+xyz);
        }
    }
}

Output:

Total Patients = 6
1.Megha
2.Reema
3.Supriya
4.Anoop
5.Sonia
6.Tejashvi
Patients recovered and discharged : [Megha, Reema, Supriya, Anoop]
Patients left in the hospital = 2
1.Sonia
2.Tejashvi

Example 3

import java.util.concurrent.ConcurrentLinkedQueue;
public class ConcurrentLinkedQueueSizeExample3 {
    public static void main(String[] args) {
        ConcurrentLinkedQueue<Integer> queue = new ConcurrentLinkedQueue<Integer>();
        queue.add(null);
        queue.add(null);
        int val =queue.size();
        System.out.println("Size of queue = "+val);
    }
}

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.util.concurrent.ConcurrentLinkedQueue.checkNotNull(ConcurrentLinkedQueue.java:920)
	at java.util.concurrent.ConcurrentLinkedQueue.offer(ConcurrentLinkedQueue.java:327)
	at java.util.concurrent.ConcurrentLinkedQueue.add(ConcurrentLinkedQueue.java:297)
	at com.javaTpoint.ConcurrentLinkedQueueSizeExample3.main(ConcurrentLinkedQueueSizeExample3.java:7)

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