Write a Java class InputStatsArray to modify the InputStats class from Practice

Question

Write a Java class InputStatsArray to modify the InputStats class from Practice Exercise 8 to:

1. Declare an int array numbers and a Scanner scanner;

2. In a loop,

a. Prompt users to input integers until they type “quit” when they’re finished;

b. Scan each integer as an int-valued numbers array element;

c. Compute the sums and squared sums of the elements in the numbers array;

3. Finally,

a. Compute the arithmetic mean (simple average) and standard deviation about the mean of the elements of the numbers array;

b. Print all the numbers on one line in format (for example):
Numbers: 1 4 33 2 5 14 22

c. Print the mean and standard deviation on the next line in the format:
Mean: 11.57142857; Std Deviation: 12.09486314

Explanation / Answer

/**The java program InputStatsArray that prompts user to
* enter numbers until user enters to quit the reading.
* Then calculates the mean and standard deviation and
* print to console*/
//InputStatsArray.java
import java.util.Scanner;
public class InputStatsArray
{
   public static void main(String[] args)
   {
      
       //Create an instance of scanner class
       Scanner scanner=new Scanner(System.in);
       int total=0;
       int count=0;
              
       //create an array of type double
       double[] arr=new double[100];
       String value;
      
       //read value from user
       System.out.println("Enter a value or enter quit: ");
       value=scanner.nextLine();
       //Check if user does not enter quit
       while(!value.equalsIgnoreCase("quit"))
       {
                       //parse to integer
           int num=Integer.parseInt(value);
           //set to array
           arr[count]=num;
           //Add to total
           total+=arr[count];
           count++;
          
           //read next vlaue
           System.out.println("Enter a value or enter quit: ");
           value=scanner.nextLine();
       }
      
       //calculate mean value
       double mean=(double)total/count;      
       double standardDeviation=0;
       total=0;
       for (int index = 0; index < count; index++)
       {
           total+=Math.pow((arr[index]-mean),2.0);
       }
      
       //calculate standard devation
       standardDeviation=Math.sqrt(total/(count-1));
      
       for (int i = 0; i < count; i++)
       {
           System.out.println(arr[i]+" ");
       }
      
       //print mean and standard deviation
       System.out.println("Mean : "+mean+";"
       +"Std Deviation:"+standardDeviation);
      
   }
}

-----------------------------------------------------------------------------------------------------------------------

Sample output:

Enter a value or enter quit:
1
Enter a value or enter quit:
4
Enter a value or enter quit:
33
Enter a value or enter quit:
2
Enter a value or enter quit:
5
Enter a value or enter quit:
14
Enter a value or enter quit:
22
Enter a value or enter quit:
quit
1.0
4.0
33.0
2.0
5.0
14.0
22.0
Mean : 11.571428571428571;Std Deviation:12.041594578792296

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.