Question

public class PracticeExam {

public static void main(String[] args) {

int[][] data = {

{ 0, 1, 2, 3, 4, 5, 6 },

{ 0, 1, 2, 3, 4, 5, 6 },

{ 0, 1, 2, 3, 4, 5, 6 },

{ 0, 1, 2, 3, 4, 5, 6 },

{ 0, 1, 2, 3, 4, 5, 6 },

{ 0, 1, 2, 3, 4, 5, 6 },

{ 0, 1, 2, 3, 4, 5, 6 },

{ 0, 1, 2, 3, 4, 5, 6 } };

// input: TODO prompt the user for

// 1) a row number

// 2) a column number

// processing: TODO implment the methods below

int rowSum = sumRow(rowNum, data);

int colSum = sumColumn(colNum, data);

double all = overallAverage(data);

// output: TODO display the three answers

// using a method named displayResults

}

}

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

// PracticeExam.java

import java.util.Scanner;

public class PracticeExam {

    /**

    * method to find the sum of elements in a specified row

    *

    * @param rowNum

    *            row number between 0 and data.length-1

    * @param data

    *            2d array

    * @return the sum of elements in rowNum row of data

    */

    static int sumRow(int rowNum, int data[][]) {

         int sum = 0;

         // looping through each column in rowNum row of data, summing values

         for (int c = 0; c < data[rowNum].length; c++) {

             sum += data[rowNum][c];

         }

         return sum;

    }

    /**

    * method to find the sum of elements in a specified column

    *

    * @param colNum

    *            column number between 0 and data[0].length-1

    * @param data

    *            2d array

    * @return the sum of elements in colNum column of data

    */

    static int sumColumn(int colNum, int data[][]) {

         int sum = 0;

         // looping through each row in data

         for (int r = 0; r < data.length; r++) {

             // adding element at row=r and column=colNum to sum

             sum += data[r][colNum];

         }

         return sum;

    }

    /**

    * method to find the average of all values in data

    *

    * @param data

    *            2d array

    * @return average in double format

    */

    static double overallAverage(int data[][]) {

         int sum = 0; // total sum

         int count = 0; // total number of cells in data array

         // looping through each row and column, summing values

         for (int r = 0; r < data.length; r++) {

             for (int c = 0; c < data[r].length; c++) {

                 sum += data[r][c];

                 count++;

             }

         }

         // finding and returning average

         double avg = (double) sum / count;

         return avg;

    }

    /**

    * method to display the results

    *

    * @param rowSum

    *            sum of elements of a specified row

    * @param colSum

    *            sum of elements of a specified column

    * @param average

    *            average of all elements in an array

    */

    static void displayResults(int rowSum, int colSum, double average) {

         System.out.println("Sum of elements in specified row: " + rowSum);

         System.out.println("Sum of elements in specified column: " + colSum);

         System.out.println("Overall average of elements: " + average);

    }

    public static void main(String[] args) {

         int[][] data = {

         { 0, 1, 2, 3, 4, 5, 6 },

         { 0, 1, 2, 3, 4, 5, 6 },

         { 0, 1, 2, 3, 4, 5, 6 },

         { 0, 1, 2, 3, 4, 5, 6 },

         { 0, 1, 2, 3, 4, 5, 6 },

         { 0, 1, 2, 3, 4, 5, 6 },

         { 0, 1, 2, 3, 4, 5, 6 },

         { 0, 1, 2, 3, 4, 5, 6 } };

         Scanner sc = new Scanner(System.in);

         // input: prompting the user for

         // 1) a row number

         System.out.print("Enter a row number: ");

         int rowNum = sc.nextInt();

         // 2) a column number

         System.out.print("Enter a column number: ");

         int colNum = sc.nextInt();

         // processing: assuming row and column numbers are valid, finding each

         // sum

         int rowSum = sumRow(rowNum, data);

         int colSum = sumColumn(colNum, data);

        

         //finding average

         double all = overallAverage(data);

         // output: displaying the three answers

         // using a method named displayResults

         displayResults(rowSum, colSum, all);

    }

}

/*OUTPUT*/

Enter a row number: 3

Enter a column number: 2

Sum of elements in specified row: 21

Sum of elements in specified column: 16

Overall average of elements: 3.0