java - 对大学餐厅的队列进行建模

Question

以下是限制条件: 餐厅每天营业时间为早上 6 点至晚上 11:59(因此在 360 分钟开门)。

平均每 5 分钟就有一位顾客来到餐厅。 (因此一分钟内有 20% 的机会找到顾客。)

餐厅需要 2 到 7 分钟才能完成一份顾客订单，而且由于整个餐厅只有一个人在运营，因此只有在将食物提供给前一位顾客后，才会为排队的下一位顾客提供服务。

虽然餐厅试图按照每个人进来的顺序为他们提供服务，但某些人群会被优先考虑。高年级学生将先于低年级学生接受服务；大三学生先于大二学生；大二学生先于大一学生。

到目前为止，我已经使用 Java 优先级队列和映射实现了下面的代码。我试图通过每个客户进来的时间(范围从 360 及以后)和他们的等级来识别他们。然而，这是我第一次使用优先级队列和映射，我不太确定我做的事情是否正确——事实上，它返回了下面的这个错误，尽管查阅了 API，但我不确定如何修复以及其他一些 java 资源:

Exception in thread "main" java.lang.ClassCastException: java.base/java.util.AbstractMap$SimpleEntry cannot be cast to java.base/java.lang.Comparable

import java.util.*;
import java.util.PriorityQueue;
import java.util.Comparator; 
import java.util.Map; 

class CustomerComparator implements Comparator<Customer>
{
   public int compare(Customer c1, Customer c2)
   {
      if(c1.grade < c2.grade)
         return 1; 
      else if(c1.grade > c2.grade)
         return -1;
      else
         return 0;  
   }
}

class Customer
{
   public int grade;
   public double waitingTime;
   
   public Customer(int grade, double waitingTime)
   {
      this.grade = grade;
      this.waitingTime = waitingTime;
   }
   
   public int getGrade()
   {
      return grade;
   }
   
   public double getWaitingTime()
   {
      return waitingTime; 
   }
}

public class RestaurantPriority
{
   public static Queue<Map.Entry<Integer, Integer>> Restaurant = new PriorityQueue<Map.Entry<Integer, Integer>>();
   public static int waitingTime = 2 + (int)(Math.random() * ((7 - 2) + 1));
   
   public static void main(String[] args)
   {
      RestaurantPriority(); 
   }
   
   public static void RestaurantPriority()
   {
      double rand = 0.0;
      boolean newCustomer = false;
      for(int i = 360; i<1440; i++)
      {
         if(Restaurant.isEmpty())
            waitingTime = 2 + (int)(Math.random() * ((7 - 2) + 1));
         if(i == 1439)
         {
            while(!Restaurant.isEmpty())
            {
               waitingTime--;
               if(waitingTime == 0)
               {
                  Restaurant.remove();
                  waitingTime = 2 + (int)(Math.random() * ((7 - 2) + 1));
               }
               System.out.println(i + ": " + Restaurant); 
               i++;
            }
         }
         rand = Math.random();
         if(rand >= 0.0 && rand < 0.2)
            newCustomer = true; 
         else
            newCustomer = false;
         if(newCustomer)
         {
            int grade = 0;
            double rand2 = Math.random();
            if(rand >= 0.0 && rand < 0.25)
               grade = 1;
            else if(rand >= 0.25 && rand < 0.5)
               grade = 2;
            else if(rand >= 0.5 && rand <0.75)
               grade = 3;
            else
               grade = 4; 
            Restaurant.add(new AbstractMap.SimpleEntry(grade,i)); 
         }
            
         if(!Restaurant.isEmpty())
         {
            waitingTime--;
            if(waitingTime == 0)
               Restaurant.poll(); 
         }
         if(!Restaurant.isEmpty() && waitingTime == 0)
         {
            waitingTime = 2 + (int)(Math.random() * ((7 - 2) + 1));
         }
         if (i<1439)
            System.out.println(i + ": " + Restaurant); 
      }
   }
}

(整个代码都写在一个文件中。我不确定这是否是相关信息，但我认为它可能会有所帮助。)

我已经被困在这个问题上几天了，我真的很感激任何帮助。

Answer 1

public class RestaurantPriority {

public static Queue<Customer> Restaurant = new PriorityQueue<Customer>(new CustomerComparator());
public static int waitingTime = 2 + (int) (Math.random() * ((7 - 2) + 1));

public static void main(String[] args) {
    RestaurantPriority();
}

public static void RestaurantPriority() {
    double rand = 0.0;
    boolean newCustomer = false;
    for (int i = 360; i < 1440; i++) {
        if (Restaurant.isEmpty()) {
            waitingTime = 2 + (int) (Math.random() * ((7 - 2) + 1));
        }
        if (i == 1439) {
            while (!Restaurant.isEmpty()) {
                waitingTime--;
                if (waitingTime == 0) {
                    Restaurant.remove();
                    waitingTime = 2 + (int) (Math.random() * ((7 - 2) + 1));
                }
                System.out.println(i + ": " + Restaurant);
                i++;
            }
        }
        rand = Math.random();
        if (rand >= 0.0 && rand < 0.2) {
            newCustomer = true;
        } else {
            newCustomer = false;
        }
        if (newCustomer) {
            int grade = 0;
            double rand2 = Math.random();
            if (rand >= 0.0 && rand < 0.25) {
                grade = 1;
            } else if (rand >= 0.25 && rand < 0.5) {
                grade = 2;
            } else if (rand >= 0.5 && rand < 0.75) {
                grade = 3;
            } else {
                grade = 4;
            }
            Restaurant.add(new Customer(grade, i));
        }

        if (!Restaurant.isEmpty()) {
            waitingTime--;
            if (waitingTime == 0) {
                Restaurant.poll();
            }
        }
        if (!Restaurant.isEmpty() && waitingTime == 0) {
            waitingTime = 2 + (int) (Math.random() * ((7 - 2) + 1));
        }
        if (i < 1439) {
            System.out.println(i + ": " + Restaurant);
        }
    }
}}