Thread: Need direction on how to get the output desired from Parking Ticket Simulator

Hello,

Before I start explaining my issue, I have researched the Parking Ticket Simulator and found many many references, but I am pretty sure that I am missing some important details.

This is an assignment, my instructor provided the ParkedCar class, ParkingTicket class, ParkingMeter class, TicketType class, and the ParkingTicketSimulator and my job is to write the Police Officer.

This is what I have written:

import java.lang.reflect.Method;
 
 
public class PoliceOfficer 
{
 
	private String name;  // name of officer.
	private String badgeNumber;  // identifier for officer.
 
	// constructor with parameter of name and badge number
	public PoliceOfficer( String name, String badgeNumber )
	{
		this.name = name;
		this.badgeNumber = badgeNumber;
	}
 
	public String getName()
	{
		return name;
	}
 
	public String getBadge()
	{
		return badgeNumber;
	}
 
 
	public ParkingTicket checkMeter(ParkingMeter parkingMeter) 
	{
		PoliceOfficer theCop = new PoliceOfficer( name, badgeNumber );
 
		ParkingTicket ticket = null;;
 
		if(parkingMeter == null )
		{
			return null;
		}
 
		if(parkingMeter.getParkedCar() == null)
		{
			return null;
		}
 
		if(parkingMeter.isExpired() == false)
		{
 
			 return null;
		}
 
		if(parkingMeter.getParkedCar().tireMarked)
		{
 
			return null;
		}
 
 
 
 
 
 
 
 
 
 
 
		return ticket = new ParkingTicket(null, theCop, parkingMeter, null);
 
 
	}
	/**
	public void setName( String name)
	{
		this.name = name;
	}
 
	public void setBadge( String badgeNumber )
	{
		this.badgeNumber = badgeNumber;
	}
 
    */
    public String toString() 
    {
        return "Officer Name: " + name + 
               " Badge Number: " + badgeNumber;
    }
 
 
 
}

the output that I am looking for is:

Parking Ticket 0001 for
Make: Yugo, model: 55, Color: RUST, License: YUGOIGO
The location was Meter number 13 at block 13 on Elm Street.
The issuing officer was Name: Barney Fife Badge Number: 12345.
The fine is $25.00.

Parking Ticket 0002 for
Make: Yugo, model: 55, Color: RUST, License: YUGOIGO
The location was Meter number 2 at block 13 on Elm Street.
The issuing officer was Name: Barney Fife Badge Number: 12345.
The fine is $35.00.

**There are quite a few more outputs like this.

I am able to get the following output:

Parking Ticket 0001 for
null
The location was Meter number 13 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00

Parking Ticket 0002 for
null
The location was Meter number 10 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00

Parking Ticket 0003 for
null
The location was Meter number 29 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00


so what am I missing in the checkMeter that will pull the car details in and the $35.00 fines.

Thanks for the help.

Here is the type of ticket that should be returned (cannot change)

enum TicketType 
{
    OVERTIME_PARKING_VIOLATION,
    EXPIRED_METER_VIOLATION
}

Here is the ParkedCar class that cannot be changed.

public class ParkedCar 
{
    String make;
    String model;
    String color;
    String license;
    boolean tireMarked;
 
    public ParkedCar( String make,
                      String model, 
                      String color, 
                      String license ) 
    {
        this.make = make;
        this.model = model;
        this.color = color;
        this.license = license;
        this.tireMarked = false;
    }
    public String getMake() 
    {
        return make;
    }
    public String getModel() 
    {
        return model;
    }
    public String getColor() 
    {
        return color;
    }
    public String getLicense() 
    {
        return license;
    }
    public boolean getTireMarked() 
    {
        return tireMarked;
    }
    public void setTireMarked() 
    {
        tireMarked = true;
    }
    public String toString()
    {
        return "Make: " + make +", model: " + model
             + ", Color: " + color + ", License: " + license;
    }
}

Here is the ParkingMeter class again cannot be changed

public class ParkingMeter 
{
 
    private final int MAX_TIME = 120; // You can only park for 2 hours.
 
    private String street;
    private String block;
    private int meterNumber;
    private ParkedCar theCar;
    private int minutesRemaining;
 
    public ParkingMeter( String street,
                         String block,
                         int meterNumber ) 
    {
        this.street = street;
        this.block = block;
        this. meterNumber = meterNumber;
        minutesRemaining = 0;
    }
    public int getMinutesRemaining() 
    {
        return minutesRemaining;
    }
    public void setMinutesRemaining( int minutesPaid ) 
    {
        if( minutesPaid < MAX_TIME ) 
        {
            this.minutesRemaining = minutesPaid;
        }
        else {
            this.minutesRemaining = MAX_TIME;
        }    
    }
    public ParkedCar getParkedCar() 
    {
        return theCar;
    }
    public void setParkedCar( ParkedCar theCar ) 
    {
        this.theCar = theCar;
    }
    public boolean isExpired() 
    {
        return minutesRemaining <= 0;
    }
    public String toString() 
    {
        return "Meter number " + meterNumber
              + " at block " + block + " on "
              + street + " street.";
    }
}

here is the ParkingTicket class, again cannot be changed

public class ParkingTicket 
{
    private static final int OVERTIME_FINE = 35;
    private static final int EXPIRED_FINE = 25;
 
    private static int currentTicketNumber = 0;
 
    private String ticketNumber;
    private TicketType theType;
    private ParkedCar theCar;
    private PoliceOfficer theCop;
    private ParkingMeter theMeter;
 
    public ParkingTicket( ParkedCar theCar, 
                          PoliceOfficer theCop,
                          ParkingMeter theMeter, 
                          TicketType theType ) 
    {
        ticketNumber = String.format("%04d", ++currentTicketNumber);
        this.theCar = theCar;
        this.theCop = theCop;
        this.theMeter = theMeter;
        this.theType = theType;
    }
    public String toString() 
    {
        String str = "Parking Ticket " + ticketNumber + " for\n";
        str += theCar + "\n";
 
        str += "The location was ";
        str += theMeter;
 
        str += "\nThe issuing officer was " + theCop + "\n";
 
        str += "The fine is $";
        if( theType == TicketType.OVERTIME_PARKING_VIOLATION ) 
        {
            str+= OVERTIME_FINE;
        }
        else 
        {
            str+= EXPIRED_FINE;
        }
        str += ".00\n";
 
        return str;
    }
}

and finally here is the tester that cannot be changed

import java.util.*; // for ArrayList
 
public class ParkingTicketSimulator 
{
    public static void main( String [ ] args ) 
    {
 
 
        // Create some parking meters numbered 1 through NUM_PARKING_METERS.
        int NUM_PARKING_METERS = 30;
        ParkingMeter[] meters = new ParkingMeter[ NUM_PARKING_METERS + 1 ];
        for( int i = 1; i < NUM_PARKING_METERS + 1; i++ ) 
        {
            meters[ i ] = new ParkingMeter( "Elm", "13", i );
            meters[ i ].setParkedCar( null );
        }
 
        // Create some cars.
        ArrayList<ParkedCar> cars = new ArrayList<ParkedCar>();
        cars.add( new ParkedCar( "Ford", "Mustang", "RED", "STANG 11" ) );
        cars.add( new ParkedCar( "Chevy", "Camaro", "BLACK", "CAM 11" ) );
        cars.add( new ParkedCar( "Toyota", "Camry", "SILVER", "ABC 123" ) );
        cars.add( new ParkedCar( "Nissan", "Stanza", "BLACK", "WAS1234" ) );
        cars.add( new ParkedCar( "Pontiac", "G5", "WHITE", "XYZ 999" ) );
        cars.add( new ParkedCar( "Honda", "Element", "GREEN", "GONE NOW" ) );
        cars.add( new ParkedCar( "Kia", "Sedona", "YELLOW", "MNP 354" ) );
        cars.add( new ParkedCar( "Audi", "S6", "SILVER", "MY AUDI" ) );
        cars.add( new ParkedCar( "Acura", "ZDX", "RED", "BIGBUCKS" ) );
        cars.add( new ParkedCar( "Lincoln", "MKZ", "BLACK", "LINC 10" ) );
        cars.add( new ParkedCar( "Volvo", "S80", "GRAY", "XED 925" ) );
        cars.add( new ParkedCar( "Hyundai", "Accent", "RED", "JDR 328" ) );
        cars.add( new ParkedCar( "Honda", "Civic", "RED", "KST 957" ) );
        cars.add( new ParkedCar( "BMW", "7", "RED", "BMW 7" ) );
        cars.add( new ParkedCar( "Lexus", "CT", "BLUE", "DHE 351" ) );
        cars.add( new ParkedCar( "Kia", "Optima", "WHITE", "LEF 291" ) );
        cars.add( new ParkedCar( "Yugo", "55", "RUST", "YUGOIGO" ) );
 
        // Park the cars and pay the meters.
        meters[ 2 ].setParkedCar( cars.get( 4 ) );
        meters[ 2 ].setMinutesRemaining( 120 );
        meters[ 5 ].setParkedCar( cars.get( 15 ) );
        meters[ 5 ].setMinutesRemaining( 45 );
        meters[ 6 ].setParkedCar( cars.get( 6 ) );
        meters[ 6 ].setMinutesRemaining( 60 );
        meters[ 8 ].setParkedCar( cars.get( 7 ) );
        meters[ 8 ].setMinutesRemaining( 90 );
        meters[ 10 ].setParkedCar( cars.get( 5 ) );
        meters[ 10 ].setMinutesRemaining( 120 );
        meters[ 13 ].setParkedCar( cars.get( 16 ) ); // The Yugo did not pay the meter!
 
        meters[ 16 ].setParkedCar( cars.get( 9 ) );
        meters[ 16 ].setMinutesRemaining( 30 );
        meters[ 28 ].setParkedCar( cars.get( 10 ) );
        meters[ 28 ].setMinutesRemaining( 120 );
        meters[ 30 ].setParkedCar( cars.get( 11 ) );
        meters[ 30 ].setMinutesRemaining( 120 );
 
 
        // Create a police officer.
        // Have cop check all the cars.
        PoliceOfficer theCop = new PoliceOfficer( "Barney Fife", "12345" );
        for( int i = 1; i < NUM_PARKING_METERS + 1; i++ ) 
        {
            // Check each car to see if ticket can be issued.
            ParkingTicket aTicket = theCop.checkMeter( meters[i] );
            if( aTicket != null )
            {
                System.out.println( aTicket );
            }
            // Chalk the tires of all cars.
            if( meters[ i ].getParkedCar() != null )
            {
                meters[ i ].getParkedCar().setTireMarked();
            }
        }
 
        // Advance the clock two hours.
        for( int i = 1; i < NUM_PARKING_METERS + 1; i++ ) 
        {
            meters[ i ].setMinutesRemaining( 0 );
        }
 
        // Some cars leave, others arrive.
        meters[ 2 ].setParkedCar( cars.get( 16 ) ); // The Yugo moves to another spot.
        meters[ 2 ].setMinutesRemaining( 120 );
        meters[ 5 ].setParkedCar( null );
        meters[ 6 ].setParkedCar( null );
        meters[ 8 ].setParkedCar( null );
        meters[ 10 ].setParkedCar( cars.get( 1 ) );
        meters[ 10 ].setMinutesRemaining( 20 );
        meters[ 13 ].setParkedCar( null );
 
        meters[ 14 ].setParkedCar( cars.get( 3 ) );
        meters[ 14 ].setMinutesRemaining( 40 );
        meters[ 15 ].setParkedCar( cars.get( 14 ) );
        meters[ 15 ].setMinutesRemaining( 120 );
        meters[ 17 ].setParkedCar( cars.get( 12 ) );
        meters[ 17 ].setMinutesRemaining( 60 );
        meters[ 21 ].setParkedCar( cars.get( 8 ) );
        meters[ 21 ].setMinutesRemaining( 120 );
        meters[ 29 ].setParkedCar( cars.get( 13 ) );
        meters[ 30 ].setMinutesRemaining( 120 );
 
        // One half hour passes before the cop checks meters.
        for( int i = 1; i < NUM_PARKING_METERS + 1; i++ ) 
        {
            meters[ i ].setMinutesRemaining( meters[ i ].getMinutesRemaining() - 30 );
        }
 
        // Cop checks meters again.
        for( int i = 1; i < NUM_PARKING_METERS + 1; i++ ) 
        {
            // Check each car to see if ticket can be issued.
            ParkingTicket aTicket = theCop.checkMeter( meters[i] );
            if( aTicket != null )
            {
                System.out.println( aTicket );
            }
            // Chalk the tires of all cars.
            if( meters[ i ].getParkedCar() != null )
            {
                meters[ i ].getParkedCar().setTireMarked();
            }
        }
    }    
}

so to answer your questions, I have tried to put system.out.println's in the police officer to find the null, but it should be coming from the ParkedCar class I believe.

I created a new police officer in the checkMeter() method because otherwise I am not pulling over the cops name and badgeNumber. Please point me in the right direction if I am doing way to much or there is something that I am missing. I have spent many hours on this one assignment which is unusual for me, but I guess I am not connecting this assignment very well.

basically I am having trouble calling methods from other classes then to display the output.

the cops name and badgeNumber

That info is in the current instance of the class. Use the this reference variable when you need to refer to the current instance of the class.

Where are these lines printed:
Parking Ticket 0001 for
null

Where does the null value come from? The desired output shows information about a car. Where does the car's information come from?

from what I can tell, the null value comes from the ParkingTicket class, where the toString is located. Is that correct? But theCar gets the variables from ParkedCar class so this is where I am getting confused. So I want to invoke theCar, but this is located in the getParkedCar() method. This is fun, but I am starting to think that this is not something for me. there are so many arguments and ifs and elses and fors and strings and I can keep going. Thank you for helping.

ok....I kind of see what you are saying. I will try to get the null issue fixed, and then get back to you.....Thank you for your help so far!

so....I placed a print line in the police officer class:

if(parkingMeter.getParkedCar() != null)System.out.println(" my car "); // trying to find the null value.

I put the statement above the last return in the checkMeter() method and I am not getting anything to print out. But, I am seeing that there is a variable in both the ParkingMeter and ParkingTicket classes. So does this mean that the ParkingTicket class is not passing the information over from the ParkedCar class?

Forget about testing it, just print it and you can see what it is:
System.out.println("parkedCar=" + parkingMeter.getParkedCar());

there is a variable in both the ParkingMeter and ParkingTicket classes.

What is the name of the variables you are talking about?

in the ParkedCar class, there is make, model, color, and license....This should by all in theCar variable.

I tried the print statement that you provided, this is what I got as an output:
parkedCar=Make: Yugo, Model: 55, Color: RUST, License: YUGOIGO
Parking Ticket 0001 for
null
The location was Meter number 13 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00

parkedCar=Make: Yugo, Model: 55, Color: RUST, License: YUGOIGO
Parking Ticket 0002 for
null
The location was Meter number 2 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00

parkedCar=Make: Chevy, Model: Camaro, Color: BLACK, License: CAM 11
Parking Ticket 0003 for
null
The location was Meter number 10 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00

Parking Ticket 0004 for
null
The location was Meter number 16 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $35.00

Parking Ticket 0005 for
null
The location was Meter number 28 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $35.00

parkedCar=Make: BMW, Model: 7, Color: RED, License: BMW 7
Parking Ticket 0006 for
null
The location was Meter number 29 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00

parkedCar=Make: Hyundai, Model: Accent, Color: RED, License: JDR 328
Parking Ticket 0007 for
null
The location was Meter number 30 at block 13 on Elm street.
The issuing officer was Officer Name: Barney Fife Badge Number: 12345
The fine is $25.00

but ticket number 4 and 5 are not pulling over the information that I need (#4: make:Lincoln, model: MKZ, Color: balck, license: LINC 10)

so do I need to create an object in the checkMeter() method for theCar? I think this is the point where I am getting confused.

 
 
 
public class PoliceOfficer 
{
 
	private String name;  // name of officer.
	private String badgeNumber;  // identifier for officer.
 
	// constructor with parameter of name and badge number
	public PoliceOfficer( String name, String badgeNumber )
	{
		this.name = name;
		this.badgeNumber = badgeNumber;
	}
 
	public String getName()
	{
		return name;
	}
 
	public String getBadge()
	{
		return badgeNumber;
	}
 
	public ParkingTicket checkMeter(ParkingMeter parkingMeter) 
	{
		PoliceOfficer theCop = new PoliceOfficer( name, badgeNumber );
		ParkingTicket ticket = null;
 
		if(parkingMeter == null )
		{
			return null;
		}
		if(parkingMeter.getParkedCar() == null)
		{
			return null;
		}
		if(parkingMeter.isExpired() == true)
		{
			 if(parkingMeter.getParkedCar().tireMarked == true)
			 {
				 return new ParkingTicket( parkingMeter.getParkedCar(), theCop, parkingMeter, TicketType.OVERTIME_PARKING_VIOLATION);
			 }
		}
		else if(parkingMeter.getParkedCar().tireMarked == false)
		{
			return null;
		}
		return ticket = new ParkingTicket(parkingMeter.getParkedCar(), theCop, parkingMeter, TicketType.EXPIRED_METER_VIOLATION);
	}
 
    public String toString() 
    {
        return "Officer Name: " + name + 
               " Badge Number: " + badgeNumber;
    }
}

So, I got all the outputs that I needed, there are some discrepancies between the fines that I got and the output that my instructor provided, but I can live with that for right now. This assignment is due tomorrow afternoon and I have been working nonstop on it since Friday, I guess this comes with the territory something new always takes longer than it should, but Norm, you have been a great help in getting me to think about what I was doing.

You still are printing a line with null. Where is that coming from? Which println statement is printing it?
Look for a println with only one item in the (). Add an ID String there for testing:
println("loc1 " + <what was there>);
Change the 1 to a 2 and 3 etc for all the places. When it prints out it will look like this:
locx null
where x will be 1 or 2 or 3 as you coded it.
Then you can find the println statement that is printing the null and see what variable is null. Then you need to find out why that variable is null.

I had a null value in the return statement, I fixed this and figured out how to get all the amounts to match up. I am turning this in before I mess anything else up and thank you again for helping me understand how to find the nulls in my code.

Glad you got it working.