package PJ3;
import java.util.*;
//--------------------------------------------------------------------------
//
// Define simulation queues in a checkout area. Queues hold references to Customer
// and Cashier objects
//
// Customer (FIFO) queue is used to hold waiting customers. If the queue is too long
// (i.e. > customerQLimnit), customer goes away without entering customer queue
//
// There are several cashiers in a checkout area. Use PriorityQueue to
// hold BUSY cashiers and FIFO queue to hold FREE cashiers,
// i.e. a cashier that is FREE for the longest time should start be used first.
//
// To handle cashier in PriorityQueue, we need to define comparator
// for comparing 2 cashier objects. Here is a constructor from Java API:
//
// PriorityQueue(int initialCapacity, Comparator<? super E> comparator)
//
// For priority queue, the default compare function is "natural ordering"
// i.e. for numbers, minimum value is returned first
//
// User can define own comparator class for PriorityQueue.
// For cashier objects, we like to have smallest end busy interval time first.
//
// The following class define compare() for two cashiers :
class CompareCashier implements Comparator<Cashier>{
// override compare() method
public int compare(Cashier o1, Cashier o2) {
return o1.getEndBusyIntervalTime() - o2.getEndBusyIntervalTime();
}
}
// DO NOT ADD NEW METHODS OR DATA FIELDS
class CheckoutArea {
// Private data fields:
// define one priority queue
private PriorityQueue <Cashier> busyCashierQ;
// define two FIFO queues
private Queue<Customer> customerQ;
private Queue<Cashier> freeCashierQ;
// define customer queue limit
private int customerQLimit;
// Constructor
public CheckoutArea()
{
}
// Constructor
public CheckoutArea(int numCashiers, int customerQlimit, int startCashierID)
{
// use ArrayDeque to construct FIFO queue objects
ArrayDeque<Customer> adCust = new ArrayDeque<Customer>();
ArrayDeque<Cashier> adCash = new ArrayDeque<Cashier>();
customerQ = new ArrayDeque<Customer>();
freeCashierQ = new ArrayDeque<Cashier>();
// construct PriorityQueue object
// override compare() in Comparator to compare Cashier objects
busyCashierQ= new PriorityQueue<Cashier>( numCashiers,
new CompareCashier());
// initialize customerQlimit
this.customerQLimit = customerQlimit;
// Construct Cashier objects and insert into FreeCashierQ
for (int i = startCashierID; i < numCashiers; i++) {
freeCashierQ.add(new Cashier(i));
}
}
public Cashier removeFreeCashierQ()
{
return freeCashierQ.poll();
}
public Cashier removeBusyCashierQ()
{
return busyCashierQ.poll();
}
public Customer removeCustomerQ()
{
return customerQ.remove();
}
public void insertFreeCashierQ(Cashier cashier)
{
freeCashierQ.add(cashier);
}
public void insertBusyCashierQ(Cashier cashier)
{
busyCashierQ.add(cashier);
}
public void insertCustomerQ(Customer customer)
{
// insert a customer
customerQ.add(customer);
}
public boolean emptyFreeCashierQ()
{
// is freeCashierQ empty?
return freeCashierQ.isEmpty();
}
public boolean emptyBusyCashierQ()
{
// is busyCashierQ empty?
return busyCashierQ.isEmpty();
}
public boolean emptyCustomerQ()
{
// is customerQ empty?
return customerQ.isEmpty();
}
public int numFreeCashiers()
{
// get number of free cashiers
return freeCashierQ.isEmpty() ? 0 : freeCashierQ.size();
}
public int numBusyCashiers()
{
// get number of busy cashiers
return busyCashierQ.isEmpty() ? 0 : busyCashierQ.size();
}
public int numWaitingCustomers()
{
// get number of customers
return customerQ.isEmpty() ? 0 : customerQ.size();
}
public Cashier getFrontBusyCashierQ()
{
// get front of busy cashiers
// "retrieve" but not "remove"
return busyCashierQ.peek();
}
public boolean isCustomerQTooLong()
{
// is customerQ too long?
return !customerQ.isEmpty() && customerQ.size() >= customerQLimit;
}
public void printStatistics()
{
System.out.println("\t# waiting customers : "+numWaitingCustomers());
System.out.println("\t# busy cashiers : "+numBusyCashiers());
System.out.println("\t# free cashiers : "+numFreeCashiers());
}
public static void main(String[] args) {
// quick check
CheckoutArea sc = new CheckoutArea(4, 5, 1001);
Customer c1 = new Customer(1,18,10);
Customer c2 = new Customer(2,33,10);
Customer c3 = new Customer(3,21,10);
Customer c4 = new Customer(3,37,10);
sc.insertCustomerQ(c1);
sc.insertCustomerQ(c2);
sc.insertCustomerQ(c3);
System.out.println(""+sc.customerQ);
System.out.println("Remove customer:"+sc.removeCustomerQ());
System.out.println("Remove customer:"+sc.removeCustomerQ());
System.out.println("Remove customer:"+sc.removeCustomerQ());
System.out.println(""+sc.freeCashierQ);
Cashier p1=sc.removeFreeCashierQ();
Cashier p2=sc.removeFreeCashierQ();
Cashier p3=sc.removeFreeCashierQ();
Cashier p4=sc.removeFreeCashierQ();
System.out.println("Remove free cashier:"+p1);
System.out.println("Remove free cashier:"+p2);
System.out.println("Remove free cashier:"+p3);
System.out.println("Remove free cashier:"+p4);
p1.freeToBusy (c1, 13);
p2.freeToBusy (c2, 13);
p3.freeToBusy (c3, 13);
p4.freeToBusy (c4, 13);
sc.insertBusyCashierQ(p1);
sc.insertBusyCashierQ(p2);
sc.insertBusyCashierQ(p3);
sc.insertBusyCashierQ(p4);
System.out.println(""+sc.busyCashierQ);
p1=sc.removeBusyCashierQ();
p2=sc.removeBusyCashierQ();
p3=sc.removeBusyCashierQ();
p4=sc.removeBusyCashierQ();
System.out.println("Remove busy cashier:"+p1);
System.out.println("Remove busy cashier:"+p2);
System.out.println("Remove busy cashier:"+p3);
System.out.println("Remove busy cashier:"+p4);
}
};
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Originally Posted by Norm
