BlockingQueue take() method in Java with examples (original) (raw)

Last Updated : 23 Aug, 2021

The take() method of BlockingQueue interface is used to retrieve and remove the head of this queue. If the queue is empty then it will wait until an element becomes available. This method is more efficient if working on threads and using BlockingQueue in that process. So the thread that initially calls take() goes to sleep if there is no element available, letting other threads do whatever they need to do.

Syntax:

public E take() throws InterruptedException

Return Value: This method returns value at the head of this BlockingQueue. If the queue is empty then it will wait until an element becomes available.
Exception: This method throws following exceptions:

• InterruptedException- When the interruption occurs at time of waiting for an element to become available if queue is empty.

Note: The take() method of BlockingQueue has been inherited from the Queue class in Java.
Below programs illustrates take() method of BlockingQueue interface:
Program 1:

Java `

// Java Program Demonstrate take() // method of BlockingQueue

import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.BlockingQueue; public class GFG {

public static void main(String[] args)
    throws InterruptedException
{
    // define capacity of BlockingQueue
    int capacityOfQueue = 4;

    // create object of BlockingQueue
    BlockingQueue<String> BQ
        = new LinkedBlockingQueue<String>(capacityOfQueue);

    // Add element to BlockingQueue
    BQ.add("Ravi");
    BQ.add("Suraj");
    BQ.add("Harsh");
    BQ.add("Sayan");

    // print elements of queue
    System.out.println("Items in Queue are " + BQ);

    // remove two elements from queue from head
    // Applying take() method on queue to remove element
    String removedItem1 = BQ.take();

    // print removedItem and queue
    System.out.println("Removed Item from head is "
                       + removedItem1);

    // print elements of queue after removing first item
    System.out.println("Remaining Items in Queue are "
                       + BQ);

    // Applying take() method on queue to remove another element
    String removedItem2 = BQ.take();

    // print removedItem and queue
    System.out.println("Removed Item from head is "
                       + removedItem2);

    // print elements of queue after removing first item
    System.out.println("Remaining Items in Queue are "
                       + BQ);
}

}

`

Output:

Items in Queue are [Ravi, Suraj, Harsh, Sayan] Removed Item from head is Ravi Remaining Items in Queue are [Suraj, Harsh, Sayan] Removed Item from head is Suraj Remaining Items in Queue are [Harsh, Sayan]

Program 2:

Java `

// Java Program Demonstrate take() // method of BlockingQueue

import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.BlockingQueue;

public class GFG {

public void takeDemo() throws InterruptedException
{
    // define capacity of BlockingQueue
    int capacityOfQueue = 5;

    // create object of BlockingQueue
    BlockingQueue<Employee> BQ
        = new LinkedBlockingQueue<Employee>(capacityOfQueue);

    // Add element to BlockingQueue
    Employee emp1 = new Employee("Ravi", "Tester", "39000");
    Employee emp2 = new Employee("Sanjeet", "Manager", "98000");

    // Add Employee Objects to BQ
    BQ.add(emp1);
    BQ.add(emp2);

    // remove elements from the queue
    // and follow this process again and again
    // until the queue becomes empty
    while (BQ.size() != 0) {

        // Remove Employee item from BlockingQueue
        // using take()
        Employee removedEmp = BQ.take();

        // print removedItem
        System.out.println("Removed Item is :");
        System.out.println("Employee Name - "
                           + removedEmp.name);
        System.out.println("Employee Position - "
                           + removedEmp.position);
        System.out.println("Employee Salary - "
                           + removedEmp.salary);

        // find size of BQ
        int size = BQ.size();

        // print remaining capacity value
        System.out.println("\nSize of list :" + size + "\n");
    }
}

// create an Employee Object with name,
// position and salary as an attribute
public class Employee {

    public String name;
    public String position;
    public String salary;

    Employee(String name, String position, String salary)
    {
        this.name = name;
        this.position = position;
        this.salary = salary;
    }

    @Override
    public String toString()
    {
        return "Employee [name=" + name + ", position="
            + position + ", salary=" + salary + "]";
    }
}

// Main Method
public static void main(String[] args)
{
    GFG gfg = new GFG();
    try {
        gfg.takeDemo();
    }
    catch (Exception e) {
        e.printStackTrace();
    }
}

}

`

Output:

Removed Item is : Employee Name - Ravi Employee Position - Tester Employee Salary - 39000

Size of list :1

Removed Item is : Employee Name - Sanjeet Employee Position - Manager Employee Salary - 98000

Size of list :0