Help with a Target Heart rate program

[KoreyAusTex]

These are the instructions, I am not asking anyone to code for me but would like to hear some ideas on how to start, this just trying to figure it out thing isn't working in this case!

Write a program, HeartRates.java, that takes as input a series of name and age pairs, prints out heart rates for exercising, and continues until either the user types "q" or 4 iterations have been executed.

Computing heart rates for exercising (press q to exit)
-----------------------------------------------
Name: John
Enter age: 20
John for your age: 20
Your aerobic zone is: 150
Your fat Burning zone is: 130

Computing heart rates for exercising (press q to exit)
-----------------------------------------------
Name: Jack
Enter age: aaa
Error! Check age again.

Computing heart rates for exercising (press q to exit)
-----------------------------------------------
Name: Joe
Enter age: 21
Joe for your age: 21
Your aerobic zone is: 149
Your fat Burning zone is: 129

Program terminating. Bye!

if you have any ideas would love to hear them, yes I need to learn this on my own but my professor acts like we already should know how to program.

[horace1]

are you working in C or C++ ?

start by writing a program to read data on one person, e.g.
(1) prompt user to enter his/her name;
(2) read the name into a char array if working in C or a string if in C++
(3) display name to check it was read OK
(4) prompt use to enter age
(5) read age into a float
(6) display age to check it is OK
(7) calculate results

when that is working you can add error echecking, e.g. if a numeric value is not entered for age, then add a loop to deal with more than one person

[Ganon11]

are you working in C or C++ ?

Seeing as this is the Java forum, I'd assume he's using Java, horace...XD

What version of Java are you running? What algorithm will you be using to calculate the output?

What code have you written so far?

[horace1]

Seeing as this is the Java forum, I'd assume he's using Java, horace...XD

guess you a right there Gannon11 !
I code in both all the time so I often find I am writing C++ in a java program, etc etc!

my idea is now
start by writing a program to read data on one person, e.g.
(1) prompt user to enter his/her name;
(2) read the name into a String
(3) display name to check it was read OK
(4) prompt use to enter age
(5) read age into a float
(6) display age to check it is OK
(7) calculate results

when that is working you can add error echecking, e.g. if a numeric value is not entered for age, then add a loop to deal with more than one person

[KoreyAusTex]

public class HeartRates
{
   static final int MAX_HEART_RATE = 220; // cannot change
 
   public static void main(String[] args)
   {
       boolean notQuit = true;
       System.out.println("Computing heart rates for exercising (press 'q' to exit)");
       System.out.println("--------------------------------------------------------");
 
       int i = 0;
 
       Scanner read = new Scanner(System.in);
 
       System.out.print("Enter your name: ");
 
       while(notQuit && i < 4){
 
 
 
           String name = read.next();
           System.out.println();
 
           if( name.charAt(0) == 'q'){
               notQuit = false;
               System.out.print("Program terminating. Bye!");
           }   else{
               System.out.print(name + " enter your age: ");
 
               double age = read.nextDouble();
                   if (age = true){
                       System.out.println("Error! Check age again.");
                   }
 
               System.out.println();
               double newZone = calcAerobicZone(age);
               double newFat = calcFatBurningZone(age);
               System.out.println( name + " your age is " + age);
               System.out.println("Your aerobic zone is: " + newZone);
               System.out.println("Your fat burning zone is: " + newFat);
 
 
               System.out.println("Computing heart rates for exercising (press 'q' to exit)");
               System.out.println("--------------------------------------------------------");
               System.out.print("Name: ");
               i++;
 
           }
 
       }
   }
 
 
   public static double calcAerobicZone(double age)
   {
       double aerobicZone = (MAX_HEART_RATE - age) * .75;
       return aerobicZone;
 
   }
 
   public static double calcFatBurningZone(double age)
   {
       double fatBurningZone = (MAX_HEART_RATE - age) * .65;
       return fatBurningZone;
 
   }
}
 

This is about all I have but I am having problems debugging.

[horace1]

fixed a couple of errors - try now

import java.util.Scanner;  // ** for Scanner
 
public class HeartRates
{
   static final int MAX_HEART_RATE = 220; // cannot change
 
   public static void main(String[] args)
   {
       boolean notQuit = true;
       System.out.println("Computing heart rates for exercising (press 'q' to exit)");
       System.out.println("--------------------------------------------------------");
 
       int i = 0;
 
       Scanner read = new Scanner(System.in);
 
       System.out.print("Enter your name: ");
 
       while(notQuit && i < 4){
 
 
 
           String name = read.next();
           System.out.println();
 
           if( name.charAt(0) == 'q'){
               notQuit = false;
               System.out.print("Program terminating. Bye!");
           }   else{
               System.out.print(name + " enter your age: ");
 
               double age = read.nextDouble();
                   if (age > 0){        // ** what test do you want here?
                       System.out.println("Error! Check age again.");
                   }
 
               System.out.println();
               double newZone = calcAerobicZone(age);
               double newFat = calcFatBurningZone(age);
               System.out.println( name + " your age is " + age);
               System.out.println("Your aerobic zone is: " + newZone);
               System.out.println("Your fat burning zone is: " + newFat);
 
 
               System.out.println("Computing heart rates for exercising (press 'q' to exit)");
               System.out.println("--------------------------------------------------------");
               System.out.print("Name: ");
               i++;
 
           }
 
       }
   }
 
 
   public static double calcAerobicZone(double age)
   {
       double aerobicZone = (MAX_HEART_RATE - age) * .75;
       return aerobicZone;
 
   }
 
   public static double calcFatBurningZone(double age)
   {
       double fatBurningZone = (MAX_HEART_RATE - age) * .65;
       return fatBurningZone;
 
   }
}

[KoreyAusTex]

actually I need the program to show the ERROR message when someone inputs something other than an number.

[KoreyAusTex]

Purpose: In this assignment, you will learn how to get input from users with the scanner class, print output with slightly more sophistication, use while loops with boolean logic, and use methods to eliminate unnecessary redundancy. When you finish this lab, you will have the basic skills for input and output to your program, and thus a start on being able to more easily debug your programming errors.

You will write a program, HeartRates.java, that takes as input a series of name and age pairs, prints out heart rates for exercising, and continues until either the user types "q" or 4 iterations have been executed. Below is a sample output from an execution of the program:

Computing heart rates for exercising (press q to exit)
-----------------------------------------------
Name: John
Enter age: 20
John for your age: 20
Your aerobic zone is: 150
Your fat Burning zone is: 130

Computing heart rates for exercising (press q to exit)
-----------------------------------------------
Name: Jack
Enter age: aaa
Error! Check age again.

Computing heart rates for exercising (press q to exit)
-----------------------------------------------
Name: Joe
Enter age: 21
Joe for your age: 21
Your aerobic zone is: 149
Your fat Burning zone is: 129

Program terminating. Bye!

In oder to compute the aerobic and fat burning zone you will use the formulas:

aerobic zone = MAX_HEART_RATE - age) * .75

fat burning zone = MAX_HEART_RATE - age) * .65

where MAX_HEART_RATE is 220 and aerobic zone is and fat burning zone are integer numbers.

The calculation of each zone should be enclosed in a method, which will be called at the appropriate place in your program. The method signatures are the following:

int calcAerobicZone(int age)

int calcFatBurningZone(int age)

You should also try to minimize the number of println() method calls in your source code. In order to do that you can use another method.

Note that only "q" should terminate the execution, all other strings are considered valid names. Your program should also contain explicit checks whether the age inserted by the user is indeed a valid number. If not, the program should print an appropriate message informing the user and should not proceed to the calculation of the two zones. If the user does not terminate the iterative process by inserting "q", the program loop should terminate after 4 tries, regardless of whether some of them are successful or not.

Tip 1: You need to put the following statement at the beginning of your class in order to tell the Java compiler where to find the Scanner class.

import java.util.*;

Tip 2: To compare two strings, you should use:

String h = "hello"
String s = "hello"
String t = "later";
h.equals(s) --> resolves to true
h.equals(t) --> resolves to false

[horace1]

the simplest thing is to use Scanner.hasNextDouble() to check if the next token is a double, if so you read it if not discard it, e.g.

// read doubles from keyboard and form sum
//  exit on a negative value
 
import java.util.Scanner;
 
public class ScanSum {
    public static void main(String[] args)  {
        Scanner s = new Scanner(System.in);
        double sum = 0;
        while (s.hasNext()) 
          {
           // if next token is a double read it and add to sum
           if (s.hasNextDouble()) 
              {
               double value = s.nextDouble();
               if(value < 0)  break;           // if token < 0 finished
               sum += value;
              } 
           else  s.next();                     // not double, discard token
            }
        System.out.println(sum);
    }
}
 

[KoreyAusTex]

how would that fit into the program, can you have two classes?

[horace1]

how would that fit into the program, can you have two classes?

have alook at this simplified version

// read doubles from keyboard and form sum
//  exit on a negative value
 
import java.util.Scanner;
 
public class ScanSum {
    public static void main(String[] args)  {
        Scanner s = new Scanner(System.in);
        double sum = 0;
        while (s.hasNext()) 
          {
           // if next token is a double read it and add to sum
           if (!s.hasNextDouble()) s.next();    // not double, discard token
           double value = s.nextDouble();
           if(value < 0)  break;           // if token < 0 finished
           sum += value;
          }
        System.out.println(sum);
    }
}
 

just insert a statement such as

      if (!s.hasNextDouble()) s.next();    // not double, discard token

before you try to read a double - it will skip anything else

[KoreyAusTex]

ok this is what I have so far but when I try to put 'q' in when prompted to enter age I get the error message intended for entering anything other than a number.

This code is starting to hurt my head anyone have any more ideas????

import java.util.*
 
public class HeartRates
{
   static final int MAX_HEART_RATE = 220; // cannot change
 
   public static void main(String[] args)
   {
       boolean notQuit = true;
       int i = 0;
       Scanner read = new Scanner(System.in); //
 
       while(notQuit && i < 4){ //looping a max of 4 times and stopping when q is entered
           System.out.println("Computing heart rates for exercising (press 'q' to exit)");
           System.out.println("--------------------------------------------------------");
           System.out.print("Name: ");
           String name = read.next();
 
           if( name.charAt(0) == 'q'){
               notQuit = false; //check to see if they entered q to stop loop
           }   else { //
               System.out.print("Enter age: ");
               try {//attempting to read a double value and catching exception that occurs
               double age = read.nextDouble();
               double newZone = calcAerobicZone(age);
               double newFat = calcFatBurningZone(age);
               System.out.println( name + " for your age: " + age);
               System.out.println("Your aerobic zone is: " + newZone);
               System.out.println("Your fat burning zone is: " + newFat + "\n");
 
               } catch (Exception e){ 
                        System.out.println("Error! Check age again.\n");
                        String garbage = read.next();
                    }
                    finally{
                        i++;
                    }
                }   
            }
            System.out.print("Program terminating. Bye!");
        }
   public static double calcAerobicZone(double age)
   {
       double aerobicZone = (MAX_HEART_RATE - age) * .75;
       return aerobicZone;
 
   }
 
   public static double calcFatBurningZone(double age)
   {
       double fatBurningZone = (MAX_HEART_RATE - age) * .65;
       return fatBurningZone;
 
   }
}

[horace1]

you have to read the faulty number as a string and check if the first character is a q, e.g.

import java.util.*;  // ** added ;
 
public class HeartRates
{
   static final int MAX_HEART_RATE = 220; // cannot change
 
   public static void main(String[] args)
   {
       boolean notQuit = true;
       int i = 0;
       Scanner read = new Scanner(System.in); //
 
       while(notQuit && i < 4){ //looping a max of 4 times and stopping when q is entered
           System.out.println("Computing heart rates for exercising (press 'q' to exit)");
           System.out.println("--------------------------------------------------------");
           System.out.print("Name: ");
           String name = read.next();
 
           if( name.charAt(0) == 'q'){
               notQuit = false; //check to see if they entered q to stop loop
           }   else { //
               System.out.print("Enter age: ");
               //attempting to read a double value and catching exception that occurs
               while (!read.hasNextDouble()) 
                  {
                   String temp = read.next();    // not double, discard token
                   if( temp.charAt(0) == 'q')
                      { System.out.print("Program terminating. Bye!"); System.exit(0); }
                   System.out.print("Error! Enter age: ");
                  }
               double age = read.nextDouble();
               double newZone = calcAerobicZone(age);
               double newFat = calcFatBurningZone(age);
               System.out.println( name + " for your age: " + age);
               System.out.println("Your aerobic zone is: " + newZone);
               System.out.println("Your fat burning zone is: " + newFat + "\n");
                        i++;
                }   
            }
            System.out.print("Program terminating. Bye!");
        }
   public static double calcAerobicZone(double age)
   {
       double aerobicZone = (MAX_HEART_RATE - age) * .75;
       return aerobicZone;
 
   }
 
   public static double calcFatBurningZone(double age)
   {
       double fatBurningZone = (MAX_HEART_RATE - age) * .65;
       return fatBurningZone;
 
   }
}

[KoreyAusTex]

When I get my output I am getting numbers like 129.000000001. How could I go about fixing this????

[horace1]

When I get my output I am getting numbers like 129.000000001. How could I go about fixing this????

you can use the System.out.printf() method (similar to C) to set the number of digits after the decimal point, see
http://java.sun.com/developer/technicalArticles/Programming/sprintf/

[KoreyAusTex]

actually I just set:

double newZone = (int) calcAerobicZone(age);
double newFat = (int) calcFatBurningZone(age);

this truncated the decimal places which works cause when your target heart rate is 127.75 the .75 is not really necessary.