Java 中的 linkedblockingrequepollast()方法

原文:https://www . geeksforgeeks . org/link edblockingeque-poll last-method-in-Java/

pollLast() 方法 link edblockingrequest返回 Deque 容器中的最后一个元素,并将其删除。如果容器是空的,它将返回空值

语法:

public E pollLast()

参数:此方法不接受任何参数。

返回:如果容器不为空,该方法返回德清容器中的最后一个元素,并删除该元素。如果容器是空的,它将返回空值

下面的程序说明了链接锁定请求的 pollLast()方法:

程序 1:

// Java Program Demonstrate pollLast()
// method of LinkedBlockingDeque

import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;

public class GFG {
    public static void main(String[] args)

    {

        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();

        // Add numbers to end of LinkedBlockingDeque
        LBD.addFirst(7855642);
        LBD.addFirst(35658786);
        LBD.addFirst(5278367);
        LBD.addFirst(74381793);

        // Print the queue
        System.out.println("Linked Blocking Deque: " + LBD);

        // prints and deletes the last element
        System.out.println("Front element in Deque: " + 
                                             LBD.pollLast());

        // prints the Deque after deletion of last element
        System.out.println("Linked Blocking Deque: " + LBD);
    }
}

输出:

Linked Blocking Deque: [74381793, 5278367, 35658786, 7855642]
Front element in Deque: 7855642
Linked Blocking Deque: [74381793, 5278367, 35658786]

程序二:

// Java Program Demonstrate pollLast()
// method of LinkedBlockingDeque
// when Deque is empty

import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;

public class GFG {
    public static void main(String[] args)

    {

        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();

        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
        LBD.add(74381793);

        // Print the queue
        System.out.println("Linked Blocking Deque: " + LBD);

        // empty deque
        LBD.clear();

        System.out.println("Front element in Deque: " + 
                                          LBD.pollLast());
    }
}

输出:

Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793]
Front element in Deque: null

参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/concurrent/linkedblockingrequest . html # pollast()