作者：儿双全id | 来源：互联网 | 2024-10-27 15:00
Java 中的 ConcurrentLinkedQueue peek()方法原文:https://www . geeksforg
Java 中的 ConcurrentLinkedQueue peek()方法
原文:https://www . geeksforgeeks . org/concurrentlinkedqueue-peek-method-in-Java/
ConcurrentLinkedQueue 的 peek() 方法用于返回 ConcurrentLinkedQueue 的头。它检索但不移除这个 ConcurrentLinkedQueue 的头。如果 ConcurrentLinkedQueue 为空，则此方法返回 null。
语法:
返回:这个方法返回这个 ConcurrentLinkedQueue 的头而不删除它。
下面的程序说明了并发链接队列的 peek()方法:
例 1:
// Java Program Demonstrate peek()
// method of ConcurrentLinkedQueue
import java.util.concurrent.*;
public class GFG {
public static void main(String[] args)
{
// create an ConcurrentLinkedQueue
ConcurrentLinkedQueue<Integer>
queue = new ConcurrentLinkedQueue<Integer>();
// Add Numbers to queue
queue.add(4353);
queue.add(7824);
queue.add(78249);
queue.add(8724);
// Displaying the existing ConcurrentLinkedQueue
System.out.println("ConcurrentLinkedQueue: " + queue);
// find peek
int response1 = queue.peek();
// print after applying peek method
System.out.println("Head: " + response1);
// Verifying that the head is not removed
System.out.println("ConcurrentLinkedQueue after peek: " + queue);
}
}
输出:
ConcurrentLinkedQueue: [4353, 7824, 78249, 8724]
Head: 4353
ConcurrentLinkedQueue after peek: [4353, 7824, 78249, 8724]
例 2:
// Java Program Demonstrate peek()
// method of ConcurrentLinkedQueue
import java.util.concurrent.*;
public class GFG {
public static void main(String[] args)
{
// create an ConcurrentLinkedQueue
ConcurrentLinkedQueue<String>
queue = new ConcurrentLinkedQueue<String>();
// Add String to queue
queue.add("Aman");
queue.add("Amar");
queue.add("Sanjeet");
queue.add("Rabi");
// Displaying the existing ConcurrentLinkedQueue
System.out.println("ConcurrentLinkedQueue: " + queue);
// find peek of queue
String response1 = queue.peek();
// print after applying peek method
System.out.println("Head: " + response1);
// Verifying that the head is not removed
System.out.println("ConcurrentLinkedQueue after peek: " + queue);
// remove some elements
queue.poll();
queue.poll();
// Displaying the existing ConcurrentLinkedQueue
System.out.println("Updated ConcurrentLinkedQueue: " + queue);
// find peek of queue
String response2 = queue.peek();
// print after applying peek method
System.out.println("Head: " + response1);
// Verifying that the head is not removed
System.out.println("ConcurrentLinkedQueue after peek: " + queue);
}
}
输出:
ConcurrentLinkedQueue: [Aman, Amar, Sanjeet, Rabi]
Head: Aman
ConcurrentLinkedQueue after peek: [Aman, Amar, Sanjeet, Rabi]
Updated ConcurrentLinkedQueue: [Sanjeet, Rabi]
Head: Aman
ConcurrentLinkedQueue after peek: [Sanjeet, Rabi]
参考:https://docs . Oracle . com/javase/8/docs/API/Java/util/concurrentlinkedqueue . html # peek–
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