Java 中的 concurrentlinkedrequeremovefirst()方法

原文:https://www . geeksforgeeks . org/concurrentlinkedeque-remove first-method-in-Java/

concurrentlinkeDeque . removefirst()是 Java 中的内置函数，它从 deque 容器中移除第一个元素。如果这个德格为空，函数抛出 NoSuchElementException 。

语法:

Conn_Linked_Deque.removeFirst()

参数:函数不接受任何参数。

返回值:该函数返回 deque 中的第一个元素。

异常:如果这个德格为空，函数抛出 NoSuchElementException 。

下面的程序说明了 removeFirst()方法:

程序 1: 该程序涉及带有整数元素的德格。

// Java Program to demonstrate removeFirst() 
// method of ConcurrentLinkedDeque   

import java.util.concurrent.*;

class ConcurrentLinkedDequeDemo {
    public static void main(String[] args)
    {
        ConcurrentLinkedDeque<Integer> cld = 
                       new ConcurrentLinkedDeque<Integer>();

        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]

节目 2: 这个节目涉及到带有弦元素的德格。

// Java Program Demonstrate removeFirst() 
// method of ConcurrentLinkedDeque   

import java.util.concurrent.*;

class ConcurrentLinkedDequeDemo {
    public static void main(String[] args)
    {
        ConcurrentLinkedDeque<String> cld = 
                      new ConcurrentLinkedDeque<String>();

        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://docs . Oracle . com/javase/8/docs/API/Java/util/concurrentlinkedeque . html # removeFirst()

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