Java中的 LinkedBlockingQueue remainingCapacity() 方法

LinkedBlockingQueue 的剩余容量()方法返回可以添加到 LinkedBlockingQueue 而不阻塞的更多元素的数量。
ThrCapacityreturned出现三种情况：

• 如果剩余容量为零，则无法将更多元素添加到 LinkedBlockingQueue。
• 如果 LinkedBlockingQueue 的剩余容量等于队列的大小，则无法从队列中删除任何元素，因为在这种情况下队列为空。
• 在任何其他情况下，Capacity 始终等于此 LinkedBlockinQueue 的初始容量与此 LinkedBlockingQueue 的当前大小之间的差。

句法：

public int remainingCapacity()

返回值：该方法返回LinkedBlockingQueue的剩余容量。

下面的程序说明了 LinkedBlockingQueue 类的剩余容量（）方法：

程序 1：使用 remainingCapacity() 方法返回 LinkedBlockingQueue 的剩余容量，其中 LinkedBlockingQueue 包含名称列表。

// 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 linkedQueue
            = new LinkedBlockingQueue(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);
    }
}

输出：

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

程序 2：查找包含员工列表的 LinkedBlockingQueue 的剩余容量。

// Java Program Demonstrate peek()
// 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 linkedQueue
            = new LinkedBlockingQueue(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();
    }
}

输出：

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

参考： https: Java/util/concurrent/LinkedBlockingQueue.html#remainingCapacity–