Java LinkedTransferQueue poll()方法
java.util.concurrent.LinkedTransferQueue.poll() 方法是Java中的一个内置函数,如果队列不是空的,它可以检索并删除队列的头部。
语法
LinkedTransferQueue.poll()
参数: 该函数不接受任何参数。
返回值: 如果队列不是空的,该函数返回队列的头部,否则返回null。
下面的程序说明了LinkedTransferQueue.poll()方法。
程序1 :
/* Java Program Demonstrate poll()
method of LinkedTransferQueue */
import java.util.concurrent.LinkedTransferQueue;
class LinkedTransferQueuePollExample1 {
public static void main(String[] args)
{
// Initializing the queue
LinkedTransferQueue<Character> queue =
new LinkedTransferQueue<Character>();
// Adding elements to this queue
for (char ch = 'A'; ch <= 'Z'; ch++) {
queue.add(ch);
}
// Printing the head of the queue
System.out.println("The head of the queue is "
+ queue.poll());
// Printing remaining elements of the queue
System.out.println("The elements in the queue :");
for (Character i : queue)
System.out.print(i + " ");
}
}
输出:
The head of the queue is A
The elements in the queue :
B C D E F G H I J K L M N O P Q R S T U V W X Y Z
示例2
/* Java Program Demonstrate poll()
method of LinkedTransferQueue */
import java.util.concurrent.LinkedTransferQueue;
class LinkedTransferQueuePollExample2 {
public static void main(String[] args)
{
// Initializing the queue
LinkedTransferQueue<Integer> queue =
new LinkedTransferQueue<Integer>();
// Adding elements to this queue
for (int i = 10; i <= 50; i += 10)
queue.add(i);
// Printing the head of the queue
System.out.println("The head of the queue is "
+ queue.poll());
// Printing remaining elements of the queue
System.out.println("The elements in the queue :");
for (Integer i : queue)
System.out.print(i + " ");
}
}
输出:
The head of the queue is 10
The elements in the queue :
20 30 40 50
参考资料 : https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedTransferQueue.html#poll()