当前位置: 首页>>代码示例 >>用法及示例精选 >>正文


Java ConcurrentLinkedQueue peek()用法及代码示例


ConcurrentLinkedQueue的peek()方法用于返回ConcurrentLinkedQueue的头。它检索但不删除此ConcurrentLinkedQueue的头部。如果ConcurrentLinkedQueue为空,则此方法返回null。

用法:

public E peek()

返回值:此方法返回此ConcurrentLinkedQueue的头部,而不删除它。


以下示例程序旨在说明ConcurrentLinkedQueue的peek()方法:

示例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]

示例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/concurrent/ConcurrentLinkedQueue.html#peek–



相关用法


注:本文由纯净天空筛选整理自AmanSingh2210大神的英文原创作品 ConcurrentLinkedQueue peek() method in Java。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。