Java ArrayBlockingQueue offer() Method

The offer() method of Java ArrayBlockingQueue class adds the defined element at the tail of this queue, only if the queue is not full or it waits till the specified wait time for space to get free, if the queue is full.

Syntax:

1.public boolean offer(E e)
2.public boolean offer(E e,long timeout,TimeUnit unit)throws InterruptedException

Parameters:

e - This is the element to be added.

timeout - This is the time to wait before giving up(in units of unit).

unit - This is the TimeUnit deciding how to represent the timeout parameter.

Specified By:

The offer() method of ArrayBlockingQueue class is specified by:

offer() method in interface Queue<E>.
offer() method in interface BlockingQueue<E>.

Throws:

The offer() method throws:

NullPointerException - if the element defined holds null value.
InterruptedException - if method is disrupted while waiting.

Return Value:

The offer() method returns true on successful insertion, otherwise returns false.

The offer() method returns true on successful insertion, or false if the assigned waiting time passes before space is available.

Example 1

import java.util.Iterator;
import java.util.concurrent.ArrayBlockingQueue;
public class ArrayBlockingQueueOfferExample1 {
    public static void main(String[] args) {
        int capacity =100;
        ArrayBlockingQueue<Integer> queue = new ArrayBlockingQueue<Integer>(capacity);
            queue.add(567);
            queue.add(56);
            queue.add(5671);
            queue.add(5167);
            //Inserts the element at the tail of the queue
            queue.offer(5670);
            Iterator<Integer> iterator = queue.iterator();
            //Returns an iterator over the elements
            while(iterator.hasNext()){
                System.out.println(iterator.next());
            }
    }
}

Output:

Example 2

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.TimeUnit;
public class ArrayBlockingQueueOfferExample2 {
    public static void main(String[] args) throws InterruptedException {
        int capacity =5;
        ArrayBlockingQueue<String> queue = new ArrayBlockingQueue<String>(capacity);
           queue.add("Reema");
            queue.add("Rahul");
            queue.add("Rita");
            queue.add("Ramesh");
           //Inserts the element at the tail of queue,waiting up to the specified waiting time.
            queue.offer("Gita",67, TimeUnit.MILLISECONDS);
            for(String xyz:queue){
                System.out.println(xyz);
            }
    }
}

Output:

Reema
Rahul
Rita
Ramesh

Example 3

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
class Employee{
    private String f_name;
    private String l_name;
    private String email;
    public Employee(String f_name, String l_name, String email) {
        this.f_name = f_name;
        this.l_name = l_name;
        this.email = email;
    }
    public String toString(){
       return f_name+"  " +l_name+"  "+email;
    }
}
public class ArrayBlockingQueueOfferExample3 {
    public static void main(String[] args) {
        Employee employee1 = new Employee("Reema     ", "Panda   ", "reemapanda18@gamil.com");
        Employee employee2 = new Employee("Geetanjali", "Sharma  ", "geetanjaliSharma28@gamil.com");
        Employee employee3 = new Employee("Vineet    ", "Tanjea  ", "VineetTanjea56@gamil.com");
        int capacity = 100;
        BlockingQueue<Employee> queue = new ArrayBlockingQueue<Employee>(capacity);
        queue.add(employee1);
        queue.add(employee2);
        queue.add(employee3);
        Employee employee4 = new Employee("Himanshu  ", "Bhardwaj", "himanshubhardwaj0604@gamil.com");
        queue.offer(employee4);
        for (Employee xyz : queue) {
            System.out.println(xyz);
        }
    }
}

Output:

Reema       Panda     [email protected]
Geetanjali  Sharma    [email protected]
Vineet      Tanjea    [email protected]
Himanshu    Bhardwaj  [email protected]

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