第193題

Give n that the elements of a PriorityQueue are ordered according to natural ordering, and:
2. import java.util.*;
3. public class GetInLine{
4. public static void main(String[] args){
5. PriorityQueue pq = new PriorityQueue();
6. pq.add("banana");
7. pq.add("pear");
8. pq.add("apple");
9. System.out.println(pq.poll() + " " + pq.peek());
10. }
11. }

What is the result?

A. apple pear
B. banana pear
C. apple apple
D. apple banana
E. banana banana


答案：D

參考：12-4-6 Queue集合
-------------------------------------------------------
5. PriorityQueue pq = new PriorityQueue();
6. pq.add("banana");
7. pq.add("pear");
8. pq.add("apple");
PriorityQueue會先把放入的東西做升冪排序,再做先進先出的方式排序
順序為apple/banana/pear
pq.poll()//指的是把元素值取出,並從集合中移除該元素,
pq.peek()//只會取出下一個元素的值不會移除該元素