lab.util

Class CheckoutLine

java.lang.Object

lab.util.CheckoutLine

public class CheckoutLine
extends Object

A class for simulating a checkout line. A checkout line is a queue of customers.

Constructor Summary

Constructors

Constructor and Description
CheckoutLine() Create a checkout line having an empty queue of customers.

Method Summary

Methods

Modifier and Type	Method and Description
void	addCustomer(Customer c) Add a customer to the back of the line.
Customer	getCurrentCustomer() Returns a reference to the customer currently at the front of the line without removing the customer from the line.
List<Customer>	getCustomersAsList() Returns a list of this checkout line's queue of customers.
int	getNumberOfCustomers() Returns the number of customers in the checkout line.
boolean	hasCustomers() Returns true if there are customers in the checkout line , and false otherwise.
Queue<Customer>	update(double currentTime) Process as many customers as possible starting from the front of the queue given the current simulation time currentTime.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CheckoutLine

public CheckoutLine()

Create a checkout line having an empty queue of customers.

Method Detail

hasCustomers

public boolean hasCustomers()

Returns true if there are customers in the checkout line , and false otherwise.

Returns:

true if there are customers in the checkout line, and false otherwise

getNumberOfCustomers

public int getNumberOfCustomers()

Returns the number of customers in the checkout line.

Returns:

the number of customers in the checkout line

getCurrentCustomer

public Customer getCurrentCustomer()

Returns a reference to the customer currently at the front of the line without removing the customer from the line. Returns null if there are no customers in the line.

Returns:

a reference to the customer currently at the front of the line, or null if there are no customers in the line

addCustomer

public void addCustomer(Customer c)

Add a customer to the back of the line.

Parameters:

c - the customer to add to the back of the line

Precondition:

c != null

getCustomersAsList

public List<Customer> getCustomersAsList()

Returns a list of this checkout line's queue of customers. Modifying the returned list does not modify the queue of customers. The state of this checkout line's queue of customers after the method finishes is the same as when the method was invoked.

Returns:

a list containing this checkout line's queue of customers

update

public Queue<Customer> update(double currentTime)

Process as many customers as possible starting from the front of the queue given the current simulation time currentTime.

The default behaviour is to dequeue the first customer from the front of the line ignoring the time. Subclasses should override this method to process customers in the line given the current time.

Parameters:

currentTime - the current time in seconds of the simulation

Returns:

the queue of customers that have been dequeued from this line during this update; the queue is empty if there are no customers in this line