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📜  Java中的 ConcurrentLinkedDeque pollFirst() 方法

📅  最后修改于: 2022-05-13 01:54:56.635000             🧑  作者: Mango

Java中的 ConcurrentLinkedDeque pollFirst() 方法

Java.util.concurrent.ConcurrentLinkedDeque.pollFirst()是Java中的一个内置方法,它检索双端队列的第一个元素并将其删除。如果双端队列为空,则该方法返回NULL

句法:

Conn_Linked_Deque.pollFirst()

参数:此函数不接受任何参数。

返回值:该函数返回双端队列的第一个元素。如果双端队列为空,则函数返回NULL

下面的程序说明了 pollFirst() 方法的使用:

程序 1:该程序涉及带有Integer元素的双端队列。

// Java Program Demonstrate pollFirst() 
// method of ConcurrentLinkedDeque   
  
import java.util.concurrent.*;
  
class ConcurrentLinkedDequeDemo {
    public static void main(String[] args)
    {
        ConcurrentLinkedDeque cld = 
                    new ConcurrentLinkedDeque();
  
        cld.addFirst(12);
        cld.addFirst(70);
        cld.addFirst(1009);
        cld.addFirst(475);
  
        // Displaying the existing LinkedDeque
        System.out.println("Elements in"
                           + "the LinkedDeque: " + cld);
  
        // Display and remove the first element
        System.out.println("Element removed : "
                           + cld.pollFirst());
  
        // Displaying the elements
        System.out.println("Elements in"
                           + "the LinkedDeque: " + cld);
    }
}
输出:
Elements inthe LinkedDeque: [475, 1009, 70, 12]
Element removed : 475
Elements inthe LinkedDeque: [1009, 70, 12]

程序 2:该程序涉及带有String元素的双端队列。

// Java Program Demonstrate pollFirst() 
// method of ConcurrentLinkedDeque   
  
import java.util.concurrent.*;
  
class ConcurrentLinkedDequeDemo {
    public static void main(String[] args)
    {
        ConcurrentLinkedDeque cld = 
                        new ConcurrentLinkedDeque();
  
        cld.addFirst("GFG");
        cld.addFirst("Geeks");
        cld.addFirst("Gfg");
        cld.addFirst("Geeks");
  
        // Displaying the existing LinkedDeque
        System.out.println("Elements in"
                           + "the LinkedDeque: " + cld);
  
        // Display and remove the First element
        System.out.println("Element removed : "
                           + cld.pollFirst());
  
        // Displaying the elements
        System.out.println("Elements in"
                           + "the LinkedDeque: " + cld);
    }
}
输出:
Elements inthe LinkedDeque: [Geeks, Gfg, Geeks, GFG]
Element removed : Geeks
Elements inthe LinkedDeque: [Gfg, Geeks, GFG]

参考: https: Java/util/concurrent/ConcurrentLinkedDeque.html#pollFirst()