The size() method of LinkedBlockingQueue returns the number of elements that LinkedBlockingQueue contains. When queue is empty queue, size() returns 0 and when queue is full then size() returns the capacity of queue.
Syntax:
public int size()
Return Value: This method returns the number of elements in the LinkedBlockingQueue at that instant. The return type is int.
Below programs illustrates size() method of LinkedBlockingQueue class:
Program 1: Perform add and remove operation on LinkedBlockingQueue an after each operation print size of queue using size()
Java
// Java Program Demonstrate size()// method of LinkedBlockingQueueimport java.util.concurrent.LinkedBlockingQueue;public class GFG { public static void main(String[] args) throws InterruptedException { // define capacity of LinkedBlockingQueue int capacityOfQueue = 4; // create object of LinkedBlockingQueue LinkedBlockingQueue<String> linkedQueue = new LinkedBlockingQueue<String>(capacityOfQueue); // Add element using put() method linkedQueue.put("Karan"); linkedQueue.put("Suraj"); // get size of queue using size() method int size = linkedQueue.size(); // print elements of queue and size of queue System.out.println("Items in Queue are " + linkedQueue); System.out.println("Size of Queue is " + size); // add more elements linkedQueue.put("Harsh"); linkedQueue.put("Rahul"); // get size of queue using size() method size = linkedQueue.size(); // print elements of queue and size of queue System.out.println("Items in Queue are " + linkedQueue); System.out.println("Size of Queue is " + size); // try to remove element from Queue boolean try1 = linkedQueue.remove("Karan"); System.out.println("String name Karan is removed :" + try1); // get size of queue using size() method size = linkedQueue.size(); // print elements of queue and size of queue System.out.println("Items in Queue are " + linkedQueue); System.out.println("Size of Queue is " + size); }} |
Output:
Items in Queue are [Karan, Suraj] Size of Queue is 2 Items in Queue are [Karan, Suraj, Harsh, Rahul] Size of Queue is 4 String name Karan is removed :true Items in Queue are [Suraj, Harsh, Rahul] Size of Queue is 3
Program 2: Perform add and remove operation on LinkedBlockingQueue, containing Employee objects, an after each operation print size of queue using size()
Java
// Java Program Demonstrate size()// method of LinkedBlockingQueueimport java.util.Iterator;import java.util.concurrent.LinkedBlockingQueue;public class GFG { public void sizeDemo() throws InterruptedException { // define capacity of LinkedBlockingQueue int capacityOfQueue = 5; // create object of LinkedBlockingQueue LinkedBlockingQueue<Employee> linkedQueue = new LinkedBlockingQueue<Employee>(capacityOfQueue); // get size of queue using size() method int size = linkedQueue.size(); System.out.println("Size of Queue " + size); // Add element to LinkedBlockingQueue Employee emp1 = new Employee("Ranjeet", "Tester", "29000", 27); Employee emp2 = new Employee("Sanjeet", "Manager", "98000", 34); Employee emp3 = new Employee("Karan", "Analyst", "44000", 30); // Add Employee Objects to linkedQueue // Using put(E e) linkedQueue.put(emp1); linkedQueue.put(emp2); linkedQueue.put(emp3); // print details of linkedQueue System.out.println("\nAfter Adding some Elements queue has"); Iterator itr = linkedQueue.iterator(); while (itr.hasNext()) System.out.println(itr.next()); // get size of queue using size() method size = linkedQueue.size(); System.out.println("\nAfter Adding Size of Queue " + size); // remove employee2 name Sanjeet and Ranjeet from linkedQueue linkedQueue.remove(emp2); linkedQueue.remove(emp1); // print details of linkedQueue System.out.println("\nAfter removing Some Elements"); itr = linkedQueue.iterator(); while (itr.hasNext()) System.out.println(itr.next()); // get size of queue using size() method size = linkedQueue.size(); System.out.println("\nAfter removing size of Queue " + size); } // create an Employee Object with name, // position, salary and age as attributes public class Employee { public String name; public String position; public String salary; public int Age; Employee(String name, String position, String salary, int age) { this.name = name; this.position = position; this.salary = salary; this.Age = age; } @Override public String toString() { return "Employee [name=" + name + ", position=" + position + ", salary=" + salary + ", Age=" + Age + "]"; } } // Main Method public static void main(String[] args) { GFG gfg = new GFG(); try { gfg.sizeDemo(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } }} |
Output:
Size of Queue 0 After Adding some Elements queue has Employee [name=Ranjeet, position=Tester, salary=29000, Age=27] Employee [name=Sanjeet, position=Manager, salary=98000, Age=34] Employee [name=Karan, position=Analyst, salary=44000, Age=30] After Adding Size of Queue 3 After removing Some Elements Employee [name=Karan, position=Analyst, salary=44000, Age=30] After removing size of Queue 1
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/LinkedBlockingQueue.html#size–
