// FILE: Carwash.java
// This program illustrates the use of the carWashSimulate method which uses
// a simple queue to simulate cars waiting at a car wash.
import java.util.LinkedList;
import java.util.Queue;
import java.util.Scanner;
// We can do this without packages...
// just put these in the same folder.
//import edu.colorado.simulations.BooleanSource;
//import edu.colorado.simulations.Washer;
//import edu.colorado.simulations.Averager;
/******************************************************************************
* The CarWash Java application illustrates the use of
* the carWashSimulate method.
* The illustration uses the following values:
*
*
washTime = 240
*
arrivalTime = 0.0025
*
totalTime = 6000
*
*
* Java Source Code for this class:
*
* http://www.cs.colorado.edu/~main/applications/CarWash.java
*
*
* @author Michael Main
* (main@colorado.edu)
*
* @version
* Jun 12, 1998
******************************************************************************/
public class CarWash
{
/**
* The main method activates carWashSimulate with the values:
*
*
washTime = 240
*
arrivalTime = 0.0025
*
totalTime = 6000
*
*
The String argument (args) is not used in
* this implementation.
**/
public static void main(String[ ] args)
{
final int WASHTIME = 240;
final double ARRIVALPROB = 0.0025;
final int TOTALTIME = 6000;
carWashSimulate(WASHTIME, ARRIVALPROB, TOTALTIME);
}
/**
* Simulate the running of a car washer for a specified amount of time.
* @param washTime
* the number of seconds required to wash one car
* @param arrivalProb
* the probability of a customer arriving in any second, for example
* 0.1 is 10%
* @param totalTime
* the total number of seconds for the simulation
* Precondition:
* washTime and totalTime are positive;
* arrivalProb lies in the range 0 to 1.
* Postcondition:
* The method has simulated a car wash where washTime is the
* number of seconds needed to wash one car, arrivalProb is
* the probability of a customer arriving in any second, and
* totalTime is the total number of seconds for the
* simulation. Before the simulation, the method has written its three
* parameters to System.out. After the simulation, the method
* has written two pieces of information to System.out:
* (1) The number of cars washed, and (2) The average waiting time for
* customers that had their cars washed. (Customers that are still in the
* queue are not included in this average).
* @exception java.lang.IllegalArgumentException
* Indicates that one of the arguments violates the precondition.
**/
public static void carWashSimulate
(int washTime, double arrivalProb, int totalTime)
{
Queue arrivalTimes = new LinkedList( );
int next;
BooleanSource arrival = new BooleanSource(arrivalProb);
Washer machine = new Washer(washTime);
Averager waitTimes = new Averager( );
int currentSecond;
// Write the parameters to System.out.
System.out.println("Seconds to wash one car: " + washTime);
System.out.print("Probability of customer arrival during a second: ");
System.out.println(arrivalProb);
System.out.println("Total simulation seconds: " + totalTime);
// Check the precondition:
if (washTime <= 0 || arrivalProb < 0 || arrivalProb > 1 || totalTime < 0)
throw new IllegalArgumentException("Values out of range");
for (currentSecond = 0; currentSecond < totalTime; currentSecond++)
{ // Simulate the passage of one second of time.
// Check whether a new customer has arrived.
if (arrival.query( ))
arrivalTimes.add(currentSecond);
// Check whether we can start washing another car.
if ((!machine.isBusy( )) && (!arrivalTimes.isEmpty( )))
{
next = arrivalTimes.remove( );
waitTimes.addNumber(currentSecond - next);
machine.startWashing( );
}
// Subtract one second from the remaining time in the current wash cycle.
machine.reduceRemainingTime( );
}
// Write the summary information about the simulation.
System.out.println("Customers served: " + waitTimes.howManyNumbers( ));
if (waitTimes.howManyNumbers( ) > 0)
System.out.println("Average wait: " + waitTimes.average( ) + " sec");
}
}