我正在制定一个跟踪正在运行的志愿者的程序，该程序的目标是跟踪（县/县外）有多少跑步者，并显示每位志愿者的费用，然后得出总计结束。我的switch语句方法（第234行）遇到问题，该方法无法正确返回总计。它显示为$ 0，这显然是不可能的。
public class Runner
package festival;
import java.util.Scanner;
/**
* @JacobBarnard CMSY-166-001
* Assignment: Lab 04
* Due date: 04/07/2020
* Program Description: Using a sentinel controlled do while loop and selection
* statements to ask the user for data and to display information along with the total costs of their selections
*/
public class Runner
{
// declaring constants for each switch statement
public final static int FIVEK = 1, TENK = 2, HALF = 3, FULL = 4, FUN = 5;
// RUNNING COSTS [NON HOWARD COUNTY RESIDENT]
public final static int NONHC_FIVEK_COST = 40, NONHC_TENK_COST = 50, NONHC_HALF_COST = 85, NONHC_FULL_COST = 115, NONHC_FUN_COST = 25;
// RUNNING COSTS [HOWARD COUNTY RESIDENT]
public final static int HC_FIVEK_COST = 25, HC_TENK_COST = 35, HC_HALF_COST = 65, HC_FULL_COST = 85, HC_FUN_COST = 20;
public static void main(String [] args)
{
Scanner myScanner = new Scanner(System.in);
// creating/instaniating variables
int age = 0;
int countRunner = 0;
int countHCResidents = 0;
int countNonHCResidents = 0;
int numChildren = 0;
int numAdults = 0;
int numSeniors = 0;
int raceChoice = 0;
int maxChoice = 0;
int fiveKRunners = 0;
int tenKRunners = 0;
int halfMarathonRunners = 0;
int fullMarathonRunners = 0;
int funRunRunners = 0;
double totalCost = 0;
boolean HC_Resident = false;
double grandTotal = 0;
// prompt user if they would like to add a runner and error trap invalid input
System.out.println("Would you like to add a runner?");
String answer =myScanner.nextLine();
while (! (answer.equalsIgnoreCase("yes") || answer.equalsIgnoreCase("no")))
{
System.out.println("Invalid Entry. Only 'yes' or 'no' is acceptable Please reenter:");
System.out.println("Enter 'yes' or 'no'.");
answer =myScanner.nextLine();
}
// Check if runner is howard county resident
while ( answer.equalsIgnoreCase("yes") )
{
// *** TAL: Counter for number of runners. See below:
countRunner++;
System.out.println("Is the Runner a Howard County resident?");
String answer1 =myScanner.nextLine();
while (! (answer1.equalsIgnoreCase("yes") || answer1.equalsIgnoreCase("no")))
{
System.out.println("Invalid Entry. Only 'yes' or 'no' is acceptable. Please reenter:");
System.out.println("Enter 'Yes' or 'No':");
answer1 =myScanner.nextLine();
}
// Adds user to appropriate counter based on y/n
if (answer1.equalsIgnoreCase("yes"))
{
countHCResidents++;
HC_Resident = true;
}
else
{
countNonHCResidents++;
HC_Resident = false;
}
System.out.println("What is the runner's age?"); // prompt for age input
age = myScanner.nextInt();
while (age <= 0) // error trap for valid input
{
System.out.println("Invalid Entry. Age must be greater than 0. Please reenter:");
System.out.println("What is the runner's age?");
age = myScanner.nextInt();
}
// adding user to the appropriate groups based on age range
if (age < 10)
{
numChildren++;
}
else if (age >= 70)
{
numSeniors++;
}
else
{
numAdults++;
}
// Check if runner is eligible for the fun run
boolean eligibleFunRun = (age < 10 || age >= 70);
// Checking age for out of county discount
boolean getsDiscount = (age <= 18 || age >= 60);
// prompt user with running even options
System.out.println("Select the event the runner will be running in:");
System.out.println("1 - 5K");
System.out.println("2 - 10K");
System.out.println("3 - Half Marathon");
System.out.println("4 - Full Marathon");
// display only if user is eligible for the fun run
if (eligibleFunRun)
{
System.out.println("5 - 1 Mile Fun Run");
}
// storing users choice in raceChoice
raceChoice = myScanner.nextInt();
// error trap
maxChoice = (eligibleFunRun ? 5 : 4);
while( (raceChoice < 1) || (raceChoice > maxChoice) )
{
// prompt user again with menu
System.out.println("Invalid Entry. Please select a value from the menu. Please reenter: Select the event the runner will be running in:");
System.out.println("1 - 5K");
System.out.println("2 - 10K");
System.out.println("3 - Half Marathon");
System.out.println("4 - Full Marathon");
// check if user is eligible for fun run
if (eligibleFunRun)
{
System.out.println("5 - 1 Mile Fun Run");
}
// storing user input in raceChoice
raceChoice = myScanner.nextInt();
}
// Adding user appropriately to event groups
if (raceChoice == 1)
{
fiveKRunners++;
}
else if (raceChoice == 2)
{
tenKRunners++;
}
else if (raceChoice == 3)
{
halfMarathonRunners++;
}
else if (raceChoice == 4)
{
fullMarathonRunners++;
}
else
{
funRunRunners++;
}
// ----------------------------(CALCULATIONS)---------------------------------------------------------------------------------
// Calculating cost based on user input and apply necesary discounts
raceChoiceSwitch(raceChoice, totalCost, getsDiscount, HC_Resident, grandTotal);
//*** TAL: need to flush the buffer here before accepting new input with the nextLine() method.
myScanner.nextLine();
// ** TAL: Logic to prompt and determine if the loop needs to continue or not:
System.out.println("Would you like to add a runner?");
answer = myScanner.nextLine();
while (! (answer.equalsIgnoreCase("yes") || answer.equalsIgnoreCase("no")) )
{
System.out.println("Invalid Entry. Only 'yes' or 'no' is acceptable. Please reenter:");
System.out.println("Enter 'yes' or 'no'.");
answer = myScanner.nextLine();
}
} // end main while loop
// Display total amount of runners
System.out.println("Total Runners: " + countRunner);
System.out.println("Total Howard County Residents: " + countHCResidents);
System.out.println("Total Non-Howard County Residents: " + countNonHCResidents);
System.out.println("Total number of children: " + numChildren);
System.out.println("Total number of adults: " + numAdults);
System.out.println("Total number of seniors: " + numSeniors);
System.out.println("Total 5K Runners: " + fiveKRunners);
System.out.println("Total 10K Runners: " + tenKRunners);
System.out.println("Total Half Marathon Runners: " + halfMarathonRunners);
System.out.println("Total Full Marathon Runners: " + fullMarathonRunners);
System.out.println("Total Fun Run Participants: " + funRunRunners);
displayCost(totalCost); // displaying the total cost of all runners
// *** TAL: Close the input file stream before execution leaves the main method:
myScanner.close();
} // end main method
// display total cost constructor
public static void displayCost(double grandTotal)
{
System.out.printf("%s%.2f%n","\nThe total cost of all the races entered is $",grandTotal,"\n");
}
public static double calculateDiscount(double totalCost,boolean getDiscount)
{
if (getDiscount) // Checking if runner gets the out of county discount
{
totalCost -= 5;
} // end of if statement
return totalCost;
} // end of calculate cost
public static double raceChoiceSwitch(int raceChoice, double totalCost, boolean getsDiscount, boolean HC_Resident, double grandTotal) {
switch(raceChoice)
{
case FIVEK: // calculating cost of 5k
// Checking if a county resident and applying the appropriate price
if(HC_Resident == true)
{
totalCost = HC_FIVEK_COST;
System.out.printf("%s%.2f%n","You have entered the 5K race. The total cost is $",totalCost,"\n");
System.out.println();
totalCost += grandTotal;
}
else
{
totalCost = NONHC_FIVEK_COST;
totalCost = calculateDiscount(totalCost, getsDiscount);
System.out.printf("%s%.2f%n","You have entered the 5K race. The total cost is $",totalCost,"\n");
System.out.println();
totalCost += grandTotal;
} // end of FIVEK cost case
break;
case TENK: // calculating cost of 10k
// Checking if a county resident and applying the appropriate price
if(HC_Resident = true)
{
totalCost += HC_TENK_COST;
System.out.printf("%s%.2f%n","You have entered the 10K race. The total cost is $",totalCost,"\n");
System.out.println();
}
else
{
totalCost = NONHC_TENK_COST;
totalCost = calculateDiscount(totalCost, getsDiscount);
System.out.printf("%s%.2f%n","You have entered the 10K race. The total cost is $",totalCost,"\n");
System.out.println();
} // end of TENK cost case
break;
case HALF: // calculating cost of half marathon
// Checking if a county resident and applying the appropriate price
if(HC_Resident == true) {
totalCost += HC_HALF_COST;
System.out.printf("%s%.2f%n","You have entered the Half Marathon race. The total cost is $",totalCost,"\n");
System.out.println();
}
else
{
totalCost = NONHC_HALF_COST;
totalCost = calculateDiscount(totalCost, getsDiscount);
System.out.printf("%s%.2f%n","You have entered the Half Marathon race. The total cost is $",totalCost,"\n");
System.out.println();
} // end of HALF marathon cost case
break;
case FULL: // calculating cost of full marathon
// Checking if a county resident and applying the appropriate price
if(HC_Resident == true) {
totalCost += HC_FULL_COST;
System.out.printf("%s%.2f%n","You have entered the Full Marathon race. The total cost is $",totalCost,"\n");
System.out.println();
}
else
{
totalCost = NONHC_FULL_COST;
totalCost = calculateDiscount(totalCost, getsDiscount);
System.out.printf("%s%.2f%n","You have entered the Full Marathon race. The total cost is $",totalCost,"\n");
System.out.println();
} // end of full marathon cost case
break;
case FUN: // calculating cost of fun run
// Checking if a county resident and applying the appropriate price
if(HC_Resident == true) {
totalCost += HC_FUN_COST;
System.out.printf("%s%.2f%n","You have entered the Fun Run race. The total cost is $",totalCost,"\n");
System.out.println();
}
else
{
totalCost = HC_FUN_COST;
totalCost = calculateDiscount(totalCost, getsDiscount);
System.out.printf("%s%.2f%n","You have entered the Fun Run race. The total cost is $",totalCost,"\n");
System.out.println();
}
break; // end of fun run cost case
} // end of raceChoice switch
return grandTotal;
}
} // end Runner class
您在switch语句中称为totalCost += grandTotal。这会将grandTotal的值（看起来是零）添加到totalCost。我想您打算打grandTotal += totalCost。否则，每当您调用0时，您只需将totalCost += grandTotal添加到totalCost中，因为grandTotal永远不会从其0.]的起始值开始更改