LinkedBlockingQueue remainingCapacity() method in Java

Last Updated : 03 May, 2023

The remainingCapacity() method of LinkedBlockingQueue returns the number of more elements that can be added to LinkedBlockingQueue without blocking. The Capacity returned arises three cases:

If remaining Capacity is Zero, then no more elements can be added to the LinkedBlockingQueue.
If remaining Capacity of LinkedBlockingQueue is equal to the size of the Queue, then no element can be removed from the queue because in such situation queue is empty.
In any other case, Capacity is always equal to a difference between the initial capacity of this LinkedBlockingQueue and the current size of this LinkedBlockingQueue.

Syntax:

public int remainingCapacity()

Return Value: This method returns the remaining capacity of the LinkedBlockingQueue.

Below programs illustrates remainingCapacity() method of LinkedBlockingQueue class:

Program 1: Returning the remaining Capacity of the LinkedBlockingQueue using remainingCapacity() method where LinkedBlockingQueue contains list of names.

Java

// Java Program Demonstrate remainingCapacity()
// method of LinkedBlockingQueue
 
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
 
    public static void main(String[] args)
    {
        // define capacity of LinkedBlockingQueue
        int capacityOfQueue = 7;
 
        // create object of LinkedBlockingQueue
        LinkedBlockingQueue<String> linkedQueue
            = new LinkedBlockingQueue<String>(capacityOfQueue);
 
        // Add element to LinkedBlockingQueue
        linkedQueue.add("John");
        linkedQueue.add("Tom");
        linkedQueue.add("Clark");
        linkedQueue.add("Kat");
 
        // find remaining Capacity  of linkedQueue
        // using remainingCapacity() method
        int remainingCapacity = linkedQueue.remainingCapacity();
 
        // print result
        System.out.println("Queue is " + linkedQueue);
 
        // print head of queue
        System.out.println("Remaining Capacity of Queue is "
                           + remainingCapacity);
    }
}

Output:

Queue is [John, Tom, Clark, Kat]
Remaining Capacity of Queue is 3

Program 2: Finding Remaining Capacity of LinkedBlockingQueue which contains list of Employees.

Java

// Java Program Demonstrate remainingCapacity()
// method of LinkedBlockingQueue
 
import java.util.concurrent.LinkedBlockingQueue;
public class GFG {
 
    public void findPeek()
    {
        // define capacity of LinkedBlockingQueue
        int capacityOfQueue = 7;
 
        // create object of LinkedBlockingQueue
        LinkedBlockingQueue<Employee> linkedQueue
            = new LinkedBlockingQueue<Employee>(capacityOfQueue);
 
        // Add element to LinkedBlockingQueue
        Employee emp1 = new Employee("Ravi", "Tester", "39000");
        Employee emp2 = new Employee("Sanjeet", "Manager", "98000");
 
        // Add Employee Objects to linkedQueue
        linkedQueue.add(emp1);
        linkedQueue.add(emp2);
 
        // add element and find remaining capacity
        // follow same process again
        // until the queue becomes full
 
        while (linkedQueue.size() != 7) {
 
            // adding emp2 again and again to queue
            System.out.println("Adding employee is success "
                               + linkedQueue.offer(emp2));
 
            // find remaining capacity of linkedQueue
            // using remainingCapacity() method
            int remain = linkedQueue.remainingCapacity();
 
            // print remaining capacity  value
            System.out.println("Remaining Capacity of list :"
                               + remain);
        }
    }
 
    // 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();
        gfg.findPeek();
    }
}

Output:

Adding employee is success true
Remaining Capacity of list :4
Adding employee is success true
Remaining Capacity of list :3
Adding employee is success true
Remaining Capacity of list :2
Adding employee is success true
Remaining Capacity of list :1
Adding employee is success true
Remaining Capacity of list :0

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/LinkedBlockingQueue.html#remainingCapacity–