public static void main(String[] args) throws Exception {    QueueHelper.printQueue();}

public class QueueHelper {    static void printQueue() {        Queue<User> q = new PriorityQueue<>(new UserComparator());        // 添加3个元素到队列:        q.offer(new User("Bob", "A1"));        q.offer(new User("Alice", "A2"));        q.offer(new User("Boss", "V1"));        System.out.println(q.poll()); // Boss/V1        System.out.println(q.poll()); // Bob/A1        System.out.println(q.poll()); // Alice/A2        System.out.println(q.poll()); // null,因为队列为空    }}class UserComparator implements Comparator<User> {    public int compare(User u1, User u2) {        if (u1.number().charAt(0) == u2.number().charAt(0)) {            // 如果两人的号都是A开头或者都是V开头,比较号的大小:            String num1 = u1.number().substring(1);            String num2 = u2.number().substring(1);            return Integer.compare(Integer.parseInt(num1), Integer.parseInt(num2));        }        if (u1.number().charAt(0) == 'V') {            // u1的号码是V开头,优先级高:            return -1;        } else {            return 1;        }    }}record User(String name, String number) {    public String toString() {        return name + "/" + number;    }}