Odometer

[Collin Sampson]

This is my first time using instance variables and the 'new' operator, so bear with me. I am trying to make a program that functions as an odometer, with a trip odometer and total odometer. I have included a method that resets the trip odometer before each trip. There are three different trips, but within each trip there are smaller trips that accumulate on the trip odometer. The user inputs mpg and miles driven on each trip. It then ouputs their mpg, trip odometer, total odometer, and gallons of gasoline used since last reset (for each trip).

I am having a problem with the total odometer. I need it to add each trip odometer for a grand total but it is only echoing the trip odometer.
Here's my code...

import java.util.*;

public class Odometer2
{
	private double tripOdometer;
	private double addTrip;
	private double userMilesPerGallon;
	private double calculatedMilesPerGallon;
	private double gallonsOfGasoline = 0;
	private double totalOdometer;
	
	Scanner keyboard = new Scanner(System.in);
	
	public void setResetOdometer()
	{
		tripOdometer = 0;
	}	
	public void setUserMilesPerGallon()
	{
		System.out.println("Enter fuel efficiency (mpg).");
		userMilesPerGallon = keyboard.nextDouble( );
	}
	public void setTripOdometer()
	{
		System.out.println("Enter miles driven for first trip.");
		addTrip = keyboard.nextDouble( );
		while (addTrip >= 0)
		{
			tripOdometer = tripOdometer + addTrip;
			System.out.println("Enter miles driven for next trip, or -1");
			System.out.println("to exit.");
			addTrip = keyboard.nextDouble( );
		}
		totalOdometer = totalOdometer + tripOdometer;
	}
	public double getUserMilesPerGallon()
	{
		return userMilesPerGallon;
	}
	public double getGallonsOfGasoline()
	{
		gallonsOfGasoline = (tripOdometer / userMilesPerGallon);
		return gallonsOfGasoline;
	}
	public double getTripOdometer()
	{
		return tripOdometer;
	}
	public double getTotalOdometer()
	{
		return totalOdometer;
	}
	
}

And the tester...

public class Odometer2Tester
{
	public static void main (String[] args)
	{
		Odometer2 trip1 = new Odometer2();
		Odometer2 trip2 = new Odometer2();
		Odometer2 trip3 = new Odometer2();
		
		double tripOdometer1, tripOdometer2, tripOdometer3;
		double userMilesPerGallon1, userMilesPerGallon2, userMilesPerGallon3;
		double gallonsOfGasoline1 = 0, gallonsOfGasoline2 = 0, gallonsOfGasoline3 = 0;
		double totalOdometer1, totalOdometer2, totalOdometer3;
		
		trip1.setResetOdometer();
		trip1.setUserMilesPerGallon();
		userMilesPerGallon1 = trip1.getUserMilesPerGallon();
		trip1.setTripOdometer();
		tripOdometer1 = trip1.getTripOdometer();
		totalOdometer1 = trip1.getTotalOdometer();
		gallonsOfGasoline1 = trip1.getGallonsOfGasoline();
		
		trip2.setResetOdometer();
		trip2.setUserMilesPerGallon();
		userMilesPerGallon2 = trip2.getUserMilesPerGallon();
		trip2.setTripOdometer();
		tripOdometer2 = trip2.getTripOdometer();
		totalOdometer2 = trip2.getTotalOdometer();
		gallonsOfGasoline2 = trip2.getGallonsOfGasoline();
		
		trip3.setResetOdometer();
		trip3.setUserMilesPerGallon();
		userMilesPerGallon3 = trip3.getUserMilesPerGallon();
		trip3.setTripOdometer();
		tripOdometer3 = trip3.getTripOdometer();
		totalOdometer3 = trip3.getTotalOdometer();
		gallonsOfGasoline3 = trip3.getGallonsOfGasoline();
		
		System.out.println(" ");
		System.out.println(" ");
		System.out.println("For trip1, the trip odometer has been reset to zero miles.");
		System.out.println("Fuel efficiency for your vehicle: " + userMilesPerGallon1 + " mpg.");
		System.out.println("Trip odometer: " + tripOdometer1 + " miles.");
		System.out.println("Total odometer: " + totalOdometer1 + " miles.");
		System.out.println("Number of gallons of gasoline consumed since last reset: " + gallonsOfGasoline1 + " gallons.");
		
		System.out.println(" ");
		System.out.println("For trip2, the trip odometer has been reset to zero miles.");
		System.out.println("Fuel efficiency for your vehicle: " + userMilesPerGallon2 + " mpg.");
		System.out.println("Trip odometer: " + tripOdometer2 + " miles.");
		System.out.println("Total odometer: " + totalOdometer2 + " miles.");
		System.out.println("Number of gallons of gasoline consumed since last reset: " + gallonsOfGasoline2 + " gallons.");
		
		System.out.println(" ");
		System.out.println("For trip3, the trip odometer has been reset to zero miles.");
		System.out.println("Fuel efficiency for your vehicle: " + userMilesPerGallon3 + " mpg.");
		System.out.println("Trip odometer: " + tripOdometer3 + " miles.");
		System.out.println("Total odometer: " + totalOdometer3 + " miles.");
		System.out.println("Number of gallons of gasoline consumed since last reset: " + gallonsOfGasoline3 + " gallons.");
		
		
	}
}

[Claudiu Chelemen]

Hi Collin

The problem with your code is that you're using not one, but three different odometers.

Odometer2 trip1 = new Odometer2();  
Odometer2 trip2 = new Odometer2();  
Odometer2 trip3 = new Odometer2();  

Also, you should differentiate the trips and the odometer, as they're not the same thing.
Maybe you should consider chaning the structure of your Odometer class ? Think about an odometer, what is it supposed to store and what interactions can you have with it..

Claudiu