Java 中 link edblockingrequepollsfirst()方法
原文:https://www . geeksforgeeks . org/link edblockingeque-poll first-method-in-Java/
的pollsfirst()方法将链接锁定请求返回到 Deque 容器中的前端元素，并将其删除。如果容器是空的，它将返回空值。
语法:
public E pollFirst()
参数:此方法不接受任何参数。
返回:如果容器不是空的，这个方法返回前元素在德清容器中，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 pollFirst()方法:
程序 1:
// Java Program Demonstrate pollFirst()
// 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
System.out.println("Front element in Deque: " + LBD.pollFirst());
// Deque after deletion of front element
System.out.println("Linked Blocking Deque: " + LBD);
}
}
输出:
Linked Blocking Deque: [74381793, 5278367, 35658786, 7855642]
Front element in Deque: 74381793
Linked Blocking Deque: [5278367, 35658786, 7855642]
程序二:
// Java Program Demonstrate pollFirst()
// 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.pollFirst());
}
}
输出:
Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793]
Front element in Deque: null
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