示例LinkedList类的poll()，pollFirst()和pollLast()方法的程序。
LinkedList.poll()
检索并删除此列表的头部（第一个元素）。
import java.util.LinkedList;class LinkedListPollMethod{ public static void main(String[] args) { // Create a LinkedList of Strings LinkedList<String> list = new LinkedList<String>(); // Add few Elements list.add("Element1"); list.add("Element2"); list.add("Element3"); list.add("Element4"); // Display LinkList elements System.out.println("LinkedList before: "+list); /* poll(): Retrieves and removes the head (first element) * of this list. */ System.out.println("Element removed: "+list.poll()); // Displaying list elements after poll() operation System.out.println("LinkedList after: "+list); }}
输出：
LinkedList before: [Element1, Element2, Element3, Element4]Element removed: Element1LinkedList after: [Element2, Element3, Element4]
LinkedList.pollFirst()
public E pollFirst()：检索并删除此列表的第一个元素，如果此列表为空，则返回null。
import java.util.LinkedList;class LinkedListPollFirstDemo{ public static void main(String[] args) { // Create a LinkedList of Strings LinkedList<String> list = new LinkedList<String>(); // Add few Elements list.add("Element1"); list.add("Element2"); list.add("Element3"); list.add("Element4"); // Display LinkList elements System.out.println("LinkedList before: "+list); /* pollFirst(): Retrieves and removes the first element * of this list, or returns null if this list is empty. */ System.out.println("Element removed: "+list.pollFirst()); // Display list after calling pollFirst() method System.out.println("LinkedList after: "+list); }}
输出：
LinkedList before: [Element1, Element2, Element3, Element4]Element removed: Element1LinkedList after: [Element2, Element3, Element4]
LinkedList.pollLast()
public E pollLast()：检索并删除此列表的最后一个元素，如果此列表为空，则返回null。
import java.util.LinkedList;class LinkedListPollLastDemo{ public static void main(String[] args) { // Create a LinkedList of Strings LinkedList<String> list = new LinkedList<String>(); // Add few Elements list.add("Element1"); list.add("Element2"); list.add("Element3"); list.add("Element4"); // Display LinkList elements System.out.println("LinkedList before: "+list); /* pollFirst(): Retrieves and removes the first element * of this list, or returns null if this list is empty. */ System.out.println("Element removed: "+list.pollLast()); // Display after calling pollLast() method System.out.println("LinkedList after: "+list); }}输出：
LinkedList before: [Element1, Element2, Element3, Element4]Element removed: Element4LinkedList after: [Element1, Element2, Element3]
