Question

Download PartiallyFilledArray.java. Though we studied this in class, you should still take several minutes examining the code so that you understand the methods of the class.

/**

* This is a solution to the lab, "partially filled array".

*

*

*

*/

import java.util.Scanner;

public class CalculateAverage

{

public static void main(String[] args){

PartiallyFilledArray data = new PartiallyFilledArray();

getInput(data);

printResults(data);

}

  

private static void getInput(PartiallyFilledArray data) {

Scanner kbd = new Scanner(System.in);

System.out.print("Enter a number (negative will end input):");

double value = kbd.nextDouble();

while (value >= 0.0) {

data.add(value);

System.out.print("Enter a number (negative will end input):");

value = kbd.nextDouble();

}

}   

  

private static void printResults(PartiallyFilledArray data) {

int numData = data.getNumberOfElements();

double sum = 0.0;

if (numData == 0) {

System.out.println("You entered no values, so average is 0.0.");

return;

}

  

System.out.print("You entered: ");

for (int i=0; i<numData; i++) {

System.out.print(data.getElement(i)+", ");

sum+=data.getElement(i);

}

System.out.println("\nThe average is "+(sum/(double)numData));

}

}

Create a class, CalculateAverage, that prompts the user for doubles until the user enters a negative number, and then prints all the values entered by the user (not including the negative value), followed by the average of those values. Your program should use a PartiallyFilledArray to store and access the values the user provides. You may assume that the user will not enter more than 10 doubles. If the user enters only a negative value, the "average" of the values entered should be 0.

You will want to use several methods of the PartiallyFilledArray class, including an appropriate constructor, getNumberOfElements(), add(), and getElement().

Submit your CalculateAverage.java file.

Example output1:

Enter a number (negative will end input):3

Enter a number (negative will end input):5

Enter a number (negative will end input):-1

You entered: 3.0, 5.0,

The average is 4.0

Example output2:

Enter a number (negative will end input):-1

You entered no values, so average is 0.0.

Answer 1

Thanks for the question.

Here is the completed code for this problem.  Let me know if you have any doubts or if you need anything to change.

Thank You !!

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public class PartiallyFilledArray {

    private double[] array;
    private int elementCount;


    public PartiallyFilledArray() {
        array = new double[1];
        this.elementCount = 0;
    }

    public void add(double value) {

        if (elementCount == array.length) {
            double[] tempArray = new double[elementCount * 2];
            for (int i = 0; i < elementCount; i++) tempArray[i] = array[i];
            array = tempArray;
        }
        array[elementCount++] = value;

    }

    public int getNumberOfElements() {

        return elementCount;

    }

    public double getElement(int i) {
        if (0 <= i && i < elementCount) {
            return array[i];
        } else {
            return -1;
        }
    }
}

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