0.0's returned from my Average/Output

Question

I have 2 Classes, DigitMath.java and DigitMathRunner.java, the setup the lab requires uses the DigitMathRunner as the launcher for DigitMath.

My code's purpose is to show the Average of Number then output it into a sentence. The compiler gives no error but the output is below.

> > 

run DigitMathRunner

234 has a digit average of 0.0

10000 has a digit average of 0.0

111 has a digit average of 0.0

9005 has a digit average of 0.0

84645 has a digit average of 0.0

8547 has a digit average of 0.0

123456789 has a digit average of 0.0
> 

Here is the code for DigitMath.java

import static java.lang.System.*;

public class DigitMath
 {
  private int number;
  private int count;
  private int s;
  private int sum;
  private int input;
  private double average;



   public DigitMath()
 {
  number = 0;
  sum=0;
  count = 0;
  input = 0;
 }


  public DigitMath(int s)
  {
    number = s;
    input = s;
  }


   public void setNums(int s)
  {
     number = s;
     input = s;
  }


   public int sumDigits()
  {
     int sum=0;
     while(input > 0)
   { 
    sum += input % 10;
    input /= 10;
   }
     return sum;
  }


 public int countDigits()
 {
   count = (int)(Math.log10(number)+1);
   return count;
 }


 public double averageDigits()
 {
  double average = sum/count;
  return average; 
 }


 public int output()
 {
   System.out.println(""+number +" has a digit average of "+""+average);
   return number;
 }

 }

and the next block of code is the Runner.

//Name - Seth Garcia
//Date - 5/12/16
//Class - 3rd Period Monaghan
//Lab  - DigitMath

import static java.lang.System.*;

public class DigitMathRunner
{
 public static void main( String args[] )
{
   DigitMath test = new DigitMath();

      test.setNums(234);
      test.sumDigits();
      test.countDigits();
      test.averageDigits();
      test.output();

      test.setNums(10000);
      test.sumDigits();
      test.countDigits();
      test.averageDigits();
      test.output();

      test.setNums(111);
      test.sumDigits();
      test.countDigits();
      test.averageDigits();
      test.output();

      test.setNums(9005);
      test.sumDigits();
      test.countDigits();
      test.averageDigits();
      test.output();

      test.setNums(84645);
      test.sumDigits();
      test.countDigits();
      test.averageDigits();
      test.output();

      test.setNums(8547);
      test.sumDigits();
      test.countDigits();
      test.averageDigits();
      test.output();

      test.setNums(123456789);
      test.sumDigits();
      test.countDigits();
      test.averageDigits();
      test.output();
 }
}

also I am in Computer Science 1 in Highschool, if my code is bad please tell me how to improve, thanks.

Answer 1

you also could change your code and use streams for this. (only want to mention it, that you can solve a problem in different ways)

IntSummaryStatistics summaryStatistics = String.valueOf(number).chars().map(i -> i - '0').summaryStatistics();     
    System.out.println(summaryStatistics.getAverage());

.

String.valueOf(number) 

makes a String of your number

.chars()

makes a stream of the chars of your string (as int value)

.map(i -> i - '0')

subtract the intvalue of '0'

.summaryStatistics()

gives you a IntSummaryStatistics object

Answer 2

Variable shadowing is your problem.

double average = sum/count;

Remove double, please.

And force floating point division

average = sum/(double)count;

Similar problem is in sumDigits()

Additionally, you can remove the private double average entirely because it is a calculated value.

public double averageDigits()
{
    return sum/(double)count;
}

And use that method inside the output method instead of average

Answer 3

You need to use the class's members in sumDigits() and averageDigits() instead of using local variable:

public int sumDigits()
  {
   sum=0;
   while(input > 0)
   { 
    sum += input % 10;
    input /= 10;
   }
     return sum;
  }

public double averageDigits()
 {
  average = (double)sum/count;
  return average; 
 }