【发布时间】：2014-01-03 05:17:33
【问题描述】：
这些类旨在协同工作以产生如下输出：http://i.imgur.com/Plu1yU5.png 我有一个逻辑错误，不允许我为显示和/或声明为 0 的变量生成输出和数据。我已经拼命工作了好几个小时试图修复这个错误——但无济于事。如果有人能告诉我如何解决我的代码中的问题以产生我想要的输出，我将不胜感激。
这是课
/**
* This class instantiates car objects with ten private instance variables.
* It contains eight mutator methods to calculate mi/gal, distance (mi), gal/mi,
* total cost; minimum/maximum, total, and annual values for these variables within a car object.
* There are getter methods for each private instance variable.
*
* @author A. Mackey
* @version 01/02/14
*/
public class AnnualFuelUse
{
//private instance variables
private double gallonsUsed, pricePerGallon, totalCost,
minSpeed, maxSpeed,
minVariable, maxVariable, minMaxVariable,
galPerMi, miPerGal,
startingMiles, endingMiles, distance,
totalVariable[], totalValue;
//constructor with two parameters
AnnualFuelUse(int FillUpNumber, double eMiles, double sMiles, double galsUsed, double pricePerGal)
{
startingMiles = sMiles;
endingMiles = eMiles;
gallonsUsed = galsUsed;
pricePerGallon = pricePerGal;
}
//mutator method which calculates the distance drive
public void calcDistance()
{
distance = endingMiles - startingMiles;
}
//getter method to return the value of distance traveled by the object on one trip
public double getDistance()
{
return distance;
}
//mutator method which calculates gallons used per mile driven
public void calcMPG(double dist, double gallons)
{
miPerGal = dist / gallons;
}
//getter method to return the value of the miles per gallon of the object on one trip
public double getMPG()
{
return miPerGal;
}
//mutator method which calculates miles driven per gallons used
public void calcGPM(double gallons, double dist)
{
galPerMi = gallons / dist;
}
//getter method to return the value of the gallons per mile of the object on one trip
public double getGPM()
{
return galPerMi;
}
//mutator method which calculates total cost of filling up
public void totalCost()
{
totalCost = pricePerGallon * gallonsUsed;
}
//getter method to return the value of the total gasoline purchases on one trip
public double getTotalCost()
{
return totalCost;
}
//mutator method which calculates the minimum value of a given array
public void min(double minMaxVariable[])
{
minVariable = Double.MAX_VALUE;
for(int i = 0; i < minMaxVariable.length; i ++)
{
if((minMaxVariable[i]) < minVariable)
{
minVariable = minMaxVariable[i];
}
}
}
//getter method to return the minimum value of a given array
public double getMin()
{
return minVariable;
}
//mutator method which calculates the minimum value of a given array
public void max(double minMaxVariable[])
{
maxVariable = Double.MIN_VALUE;
for(int i = 0; i < minMaxVariable.length; i ++)
{
if((minMaxVariable[i]) > maxVariable)
{
maxVariable = minMaxVariable[i];
}
}
}
//getter method to return the minimum value of a given array
public double getMax()
{
return maxVariable;
}
//mutator method which calculates the total value of a given array
public void totalOf(double totalVariable[])
{
totalValue = 0;
for(double newValue : totalVariable)
{
totalValue += newValue;
}
}
//getter method to return the total value of a given array
public double getTotalOf()
{
return totalValue;
}
}
及其测试类
/**
* This class tests the AnnualFuelUse class.
*
* An array of car objects is created to hold some of the private instance variables.
*
* A for loop is used to call the variables' methods on each object.
* A second for loop is used to print an output header identifying the variables for the instance
* A third for loop is used to print the values of the instance variables for each object.
*
* @author A. Mackey
* @version 01/02/14
*/
public class AnnualFuelUseTester
{
//main method
public static void main(String[] args)
{
//declaring and initialising variables
String header = "Annual Gas Mileage Calculations",
headerLine = "===============================";
String[] headerInfo = { "Fill Up" , " Days" , " Start Miles" , " End Miles" , "Distance" , "Gallons" , " Price" , "Cost" , " Miles/Gal" , "Gal/Mile" };
int[] fillUpNumber = {1, 2, 3, 4},
daysSinceFill = {1, 4, 8, 13};
double[] startMiles = {24963, 25437, 25937, 26221},
endMiles = { 25437, 25937, 26221, 26794},
gallonsUsed = { 21.4, 21.2, 12.2, 23.7},
milesPerGallon = new double[startMiles.length],
gallonsPerMile = new double[startMiles.length],
pricePerGallon = {3.52, 3.45, 3.39, 3.41},
totalCost = new double[startMiles.length],
distance = new double[startMiles.length];
int minDistance,
maxDistance,
totalDistance,
annualDistance;
double minMPG, minCost,
maxMPG, maxCost,
totalGallonsUsed, totalCostSum,
annualGallonsUsed, annualCost, annualMPG;
//initialization of array of objects
AnnualFuelUse[] car = {new AnnualFuelUse(fillUpNumber[0], endMiles[0], startMiles[0], gallonsUsed[0], pricePerGallon[0]),
new AnnualFuelUse(fillUpNumber[1], endMiles[1], startMiles[1], gallonsUsed[1], pricePerGallon[1]),
new AnnualFuelUse(fillUpNumber[2], endMiles[2], startMiles[2], gallonsUsed[2], pricePerGallon[2]),
new AnnualFuelUse(fillUpNumber[3], endMiles[3], startMiles[3], gallonsUsed[3], pricePerGallon[3])};
//call methods
for(int index = 0; index < car.length; index++)
{
distance[index] = car[index].getDistance();
milesPerGallon[index] = car[index].getMPG();
gallonsPerMile[index] = car[index].getGPM();
totalCost[index] = car[index].getTotalCost();
}
//I desire to invoke the methods which relate to these particular variables in order to define them
minDistance = 0;
minMPG = 0;
minCost = 0;
maxDistance = 0;
maxMPG = 0;
maxCost = 0;
totalDistance = 0;
totalGallonsUsed = 0;
totalCostSum = 0;
annualDistance = 0;
annualGallonsUsed = 0;
annualCost = 0;
annualMPG = 0;
//print results
System.out.printf("%74s%n", header);
System.out.printf("%74s%n", headerLine);
for(String info : headerInfo)
{
System.out.print(info + "\t");
}
System.out.println("\n=========================================================================================================================");
for(int index = 0; index < car.length; index++)
{
System.out.printf("%4d%10d%14.0f%14.0f%12.0f%16.1f%11.2f%12.2f%12.2f%13.3f%n", fillUpNumber[index], daysSinceFill[index], startMiles[index], endMiles[index], distance[index], gallonsUsed[index], pricePerGallon[index], totalCost[index], milesPerGallon[index], gallonsPerMile[index]);
}
System.out.println("=========================================================================================================================\n");
System.out.printf("Minimum:%46d%27.2f%24.2f%n", minDistance, minMPG, minCost);
System.out.printf("Maximum:%46d%27.2f%24.2f%n%n", maxDistance, maxMPG, maxCost);
System.out.printf("Totals:%47d%16.1f%35.2f%n", totalDistance, totalGallonsUsed, totalCostSum);
System.out.printf("Annual Projection:%36d%16.1f%11.2f%24.2f%n", annualDistance, annualMPG, annualGallonsUsed, annualCost);
}
}
感谢您的帮助，谢谢。
编辑（2014 年 1 月 3 日美国东部标准时间 03:00）
pastebin.com/BRJunSvS 和 pastebin.com/kRRb0dmu 知道为什么我的 MPG 不是预计的年平均值吗？
【问题讨论】：