UserInput方法在Java中不断分配其他值

Question

this is my first question on the site. I am a fresh CS student needing some help with something that is probably really simple. The code as is will compile. When I enter in the values as the program asks, it stores the values wrong. It will store the right values for gross pay and savings rate but the IRA rate comes back as 100% even when entered at 6.9 and it seems it stores the IRA rate in saveAmount. Please halp me figure out what I am doing wrong here.

import java.text.DecimalFormat;
import java.util.*;

public class CollinDunn_1_05 {

   static Scanner console = new Scanner(System.in);
   static DecimalFormat formatCash = new DecimalFormat("#,###.00");
   static double iraTotal = 0.0;
   static double saveAmount = 0.0;
   static double totalSave = 0.0;
   static String line = "";

   public static void main (String [] args) {

      // Input variables
      double grossPay = 0.0;  // The gross pay from a users paycheck
      double saveRate = 0.0;  // This is the user entered savings rate
      double iraRate= 0.0;    // The IRA investment rate
      String whichOne = "";   // A temp variable to pass a string type into UserInput

      printInfo();                      
      grossPay = userInput("gross pay");
      saveRate = userInput("savings rate");
      iraRate = userInput("IRA rate");
      iraTotal = iraAmount(grossPay, iraRate);
      saveAmount = savingsAmount(grossPay,  saveRate);
      outputResults(grossPay, saveRate, saveAmount, iraRate, iraTotal);     

      return;      

   } // End Main

   public  static void printInfo() {

     System.out.println ("This program uses methods to calculate \n"
                                           + "savings amounts and IRA investment amounts \n"
                                           + "from user input consisiting of their gross pay, \n"
                                           + "their desired savings rate and IRA rate, made by "
                                           + " Collin Dunn");
      return;

   } // End ProgramInfo

   public static double userInput(String whichOne) {

      double saveMe = 0.0;
      System.out.print("Please enter your " + whichOne + ":    ");
      saveMe = console.nextDouble(); 

      return saveMe;

   } // End userInput

    public static double iraAmount(double grossPay, double iraRate) {                                                                                                
       iraTotal = grossPay * (iraRate / 100.0);

      return iraTotal;

   } // End iraAmount

   public static double savingsAmount(double grossPay, double saveRate) {       
      saveAmount = grossPay * (saveRate / 100.0);

      return saveAmount;

   } // End savingsAmount


   public static void outputResults(double grossPay, double saveRate, double iraRate, 
                                                                      double saveAmount, double iraTotal) {


       totalSave = saveAmount + iraTotal;

       System.out.print ("With a gross pay of $" + formatCash.format(grossPay)
                                         + ", a savings rate of %" + formatCash.format(saveRate)
                                         + " and a IRA rate of %" +formatCash.format(iraRate)
                                         + ".\n Your savings amount will be $" + formatCash.format(saveAmount)
                                         + ", with a investment amount of $" + formatCash.format(iraTotal)
                                         + ".\n Which leaves you with a total savings of $" +
                                         +  totalSave + ". Way to go for paying yourself!" );

      return;

   } // End outputResults

} //End Class

Answer 1

Your only issue is the order of arguments you pass to or have set on the outputResults() method.

Change the signature of the method to:

   public static void outputResults(double grossPay, double saveRate, double saveAmount, double iraRate, double iraTotal) {

Which now matches how you call the method:

outputResults(grossPay, saveRate, saveAmount, iraRate, iraTotal); 

Let me make a couple of additonal suggestions:

1) You are consistently naming arguments in your method signatures the same names as global variables, which makes it confusing which is which when accessing the variable in the method. Either avoid using the same names for the method input variables, or use something like this.amount = amount to make it more obvious of your intention.

2) Avoid static unless you have a valid reason to use it (which is pretty rare). Instead, take advantage of Java's Object oriented nature and create an instance of your class in the main method and call methods on that instance. This will make your code more readable, reliable, and reusable.

3) In a method that returns type 'void', you don't need to add the empty return; statement.

To correct your issue and also demonstrate the points I listed, I have refactored your code and provided it below. By the way, you have a lot of potential. Despite the fact there are a few details you can improve, for being a first year CS student, your code is well written and thought out. Good job!

import java.text.DecimalFormat;
import java.util.*;

public class CollinDunn_1_05 {

   DecimalFormat formatCash = new DecimalFormat("#,###.00");
   double iraTotal = 0.0;
   double saveAmount = 0.0;
   double totalSave = 0.0;
   double grossPay = 0.0;  // The gross pay from a users paycheck
   double saveRate = 0.0;  // This is the user entered savings rate
   double iraRate= 0.0;    // The IRA investment rate

    public CollinDunn_1_05(double gross, double saveRt, double iraRt){
      this.grossPay = gross;
      this.saveRate = saveRt;
      this.iraRate = iraRt;
    }

    public void calculate(){
      calcIraAmount();
      calcSavingsAmount();
    }

   public static void main (String [] args) {
      Scanner scanner = new Scanner(System.in);
      printInfo();                      

      CollinDunn_1_05 program = new CollinDunn_1_05(
          userInput("gross pay", scanner),
          userInput("savings rate", scanner),
          userInput("IRA rate", scanner)
        );

      program.calculate();
      program.outputResults();

   } // End Main

   public static void printInfo() {

     System.out.println ("This program uses methods to calculate \n"
                                           + "savings amounts and IRA investment amounts \n"
                                           + "from user input consisiting of their gross pay, \n"
                                           + "their desired savings rate and IRA rate, made by "
                                           + " Collin Dunn");
      return;

   } // End ProgramInfo

   public static double userInput(String whichOne, Scanner console) {
      double saveMe = 0.0;
      System.out.print("Please enter your " + whichOne + ":    ");
      saveMe = console.nextDouble(); 

      return saveMe;

   } // End userInput

    public void calcIraAmount() {    
      iraTotal = grossPay * (iraRate / 100.0);
   } // End iraAmount

   public void calcSavingsAmount() {       
      saveAmount = grossPay * (saveRate / 100.0);
   } // End savingsAmount


   public void outputResults() {
      totalSave = saveAmount + iraTotal;
      System.out.print ("With a gross pay of \$" + formatCash.format(grossPay)
                                         + ", a savings rate of %" + formatCash.format(saveRate)
                                         + " and a IRA rate of %" +formatCash.format(iraRate)
                                         + ".\n Your savings amount will be \$" + formatCash.format(saveAmount)
                                         + ", with a investment amount of \$" + formatCash.format(iraTotal)
                                         + ".\n Which leaves you with a total savings of \$" +
                                         +  totalSave + ". Way to go for paying yourself!" );

   } // End outputResults

} //End Class