LinkedBlockingQueue remainingCapacity() method in Java

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–



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