LinkedTransferQueue类的Java方法hasWaitingConsumer()

Java.util.concurrent.LinkedTransferQueue.hasWaitingConsumer()方法在以下情况下始终返回true: 如果队列中至少有一个使用BlockingQueue.take()或计时轮询等待接收元素的消费者。返回值表示瞬时状态。

语法

public boolean hasWaitingConsumer()

参数: 该方法不需要任何参数。

返回值: 该方法返回一个布尔值，如果队列中至少存在一个消费者，则返回true。

以下是几个示例，用于说明LinkedTransferQueue.hasWaitingConsumer()方法:

示例1:

// Java代码演示
// hasWaitingConsumer()方法
  
import java.util.concurrent.LinkedTransferQueue;
  
class GFG {
    public static void main(String args[])
    {
        LinkedTransferQueue<String> LTQ
            = new LinkedTransferQueue<String>();
  
        LTQ.add("Geeks");
        LTQ.add("For");
        LTQ.add("Geeks");
        LTQ.add("GeeksForGeeks");
  
        System.out.println(LTQ.hasWaitingConsumer());
    }
}

false

示例2:

// Java 代码演示
// hasWaitingConsumer() 方法
  
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedTransferQueue;
  
public class GFG {
  
    LinkedTransferQueue<Integer> LTQ
        = new LinkedTransferQueue<>();
  
    class LTQProducer implements Runnable {
  
        @Override
        public void run()
        {
            for (int i = 0; i < 3; i++) {
                try {
                    System.out.println("Producer is"
                                       + " waiting to transfer");
                    LTQ.transfer(i);
                    System.out.println("Producer transferred"
                                       + " element: "
                                       + i);
                    System.out.println("Is there any consumer"
                                       + " still waiting to"
                                       + " receive an element"
                                       + " after transfer -> "
                                       + LTQ.hasWaitingConsumer());
                }
                catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }
  
    class LTQConsumer implements Runnable {
        int id;
        LTQConsumer(int id)
        {
            this.id = id;
        }
  
        @Override
        public void run()
        {
            try {
                System.out.println("Consumer "
                                   + id
                                   + " is waiting to "
                                   + "take an element.");
                System.out.println("Is there any consumer"
                                   + " still waiting to"
                                   + " receive an element"
                                   + " after transfer -> "
                                   + LTQ.hasWaitingConsumer());
                Integer s = LTQ.take();
                System.out.println("Consumer "
                                   + id
                                   + " received Element: "
                                   + s);
            }
            catch (InterruptedException e) {
                System.out.println(e);
            }
        }
    }
  
    // Driver code
    public static void main(String[] args)
        throws InterruptedException
    {
        GFG ob = new GFG();
  
        ExecutorService exService
            = Executors.newFixedThreadPool(3);
  
        LTQProducer p = ob.new LTQProducer();
        LTQConsumer c1 = ob.new LTQConsumer(0);
        LTQConsumer c2 = ob.new LTQConsumer(1);
  
        exService.execute(p);
        exService.execute(c1);
        exService.execute(c2);
  
        exService.shutdown();
    }
}

生产者正在等待传输
消费者 0 正在等待取出一个元素。
是否有任何消费者正在等待取出元素 -> false
消费者 1 正在等待取出一个元素。
是否有任何消费者正在等待取出元素 -> false
消费者 0 接收到的元素为：0
生产者传输了元素：0
在传输元素之后是否有任何消费者仍在等待接收元素 -> true
生产者正在等待传输
生产者传输了元素：1
消费者 1 接收到的元素为：1
在传输元素之后是否有任何消费者仍在等待接收元素 -> false
生产者正在等待传输