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📜  Java中的 ConcurrentLinkedDeque removeFirst() 方法

📅  最后修改于: 2022-05-13 01:54:23.640000             🧑  作者: Mango

Java中的 ConcurrentLinkedDeque removeFirst() 方法

ConcurrentLinkedDeque.removeFirst() 是Java中的一个内置函数,它从双端队列容器中删除第一个元素。如果双端队列为空,该函数将引发NoSuchElementException

句法:

Conn_Linked_Deque.removeFirst()

参数:该函数不接受任何参数。

返回值:该函数返回双端队列中的第一个元素。

异常:如果双端队列为空,该函数将引发NoSuchElementException

下面的程序说明了 removeFirst() 方法:

程序 1:该程序涉及带有Integer元素的双端队列。

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

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