Java.util.ArrayDeque.pollFirst() Java.util.ArrayDeque.poll() Java.util.ArrayDeque.pollLast() 描述 所述java.util.ArrayDeque.pollFirst()方法检索和移除第一元件本的双端队列 .Returns 空如果此双端队列是空的。 声明 以下是java.util.ArrayDeque.pollFirst()方法的声明 public E pollFirst() 参数 NA 返回值 此方法返回此双端队列的头部,如果此双端队列为空,则返回null。 异常 NA 实例 以下示例显示了java.util.ArrayDeque.pollFirst()方法的用法。 package com.tutorialspoint; import java.util.ArrayDeque; import java.util.Deque; public class ArrayDequeDemo { public static void main(String[] args) { // create an empty array deque with an initial capacity Deque<Integer> deque = new ArrayDeque<Integer>(8); // use add() method to add elements in the deque deque.add(25); deque.add(30); deque.add(20); deque.add(18); // printing all the elements available in deque for (Integer number : deque) { System.out.println("Number = " + number); } int retval = deque.pollFirst(); System.out.println("Element removed is " + retval); // printing all the elements available in deque after using pollFirst() for (Integer number : deque) { System.out.println("Number = " + number); } } } 让我们编译并运行上面的程序,这将产生以下结果 Number = 25 Number = 30 Number = 20 Number = 18 Element removed is 25 Number = 30 Number = 20 Number = 18 Java.util.ArrayDeque.poll() Java.util.ArrayDeque.pollLast()