Question

Write the appropriate method headings using the provided method name for the following processes (2 pts each).

1. Calculate and return the sum of two decimal numbers - getSum.

2. Compute and return the average speed of a car, given the distance traveled (as type double) and traveling time (in hours and minutes, both of type int) - getAverageSpeed.

3. Given the radius of a circle, print the area of a circle - printArea.

4. Given a student’s name and three test scores (of type int), print the student’s name and average test score - printStudentDetails

A. Array Declarations(2 pts each). Determine whether the following array declarations are valid. If a declaration is valid, write VALID. If it is invalid, you can make assumptions and write a correct declaration

1. int size;

double[] list = new double[size];

2. int[] test = new int[-10];

3. double[] sales = new double[40.5];

4. int x, y;

har[][] board = new board[x][y];

Answer 1

The code for questions 1 to 4 is :

import java.util.Scanner;

public class Functions {
        
        //Question (1) getSum() function
        //This function calculates two decimal numbers and prints result
        public static void getSum() {
                float a1;
                float a2;
                //Creating a object scnr of class Scanner() to read input from user.
                Scanner scnr = new Scanner(System.in);
                System.out.printf("Enter first decimal value :");
                //Scanner object.nextInt() reads a integer value from user
                //For float numbers .nextFloat()
                //For strings nextLine()
                a1 = scnr.nextFloat();
                System.out.printf("Enter second decimal value : ");
                a2=scnr.nextFloat();
                float result=a1+a2;
                
                System.out.printf("Sum of two decimal numbers is %.2f+%.2f= %.2f\n",a1,a2,result);
                
                
        }
        
        //Question (2) getAverageSpeed()
        //This function takes distance,time as inputs and prints average speed
        //I have taken meter/second as units for speed
        public static void getAverageSpeed() {
                double distance;
                int hours;
                int minutes;
                Scanner scnr1 = new Scanner(System.in);
                System.out.printf("\nEnter distance travelled in km :");
                distance=scnr1.nextDouble();
                System.out.printf("Enter No.of hours travelled : ");
                hours =scnr1.nextInt();
                System.out.printf("Enter mins :");
                minutes = scnr1.nextInt();
                System.out.printf("The average speed of the car is: %.3f m/sec\n",(distance*1000)/((hours*60+minutes)*60));
                
        }
        
        //Question (3) printArea()
        //This function takes radius as input and prints area of circle
        public static void printArea() {
                Scanner scnr1 = new Scanner(System.in);
                System.out.printf("\nEnter radius of circle: ");
                float radius=scnr1.nextFloat();
                System.out.printf("Area of circle with radius %f is %f\n",radius,(3.14*radius*radius));
                
        }
        
        //Question (4) printStudentDetails()
        public static void printStudentDetails() {
                Scanner scnr1 = new Scanner(System.in);
                System.out.printf("\nEnter student name: ");
                String name =scnr1.nextLine();
                System.out.printf("Enter score 1: ");
                int score1=scnr1.nextInt();
                System.out.printf("Enter score 2: ");
                int score2=scnr1.nextInt();
                System.out.printf("Enter score 3: ");
                int score3=scnr1.nextInt();
                float avg= (score1+score2+score3)/3;
                System.out.printf("Average score of student %s in 3 tests is: %.2f",name,avg);
                
        }
        
        //Program execution starts from main() function
        //Every other function is executed only when it is called by main() function
        public static void main(String[] args) {
                //Calling functions one by one
                getSum();
                getAverageSpeed();
                printArea();
                printStudentDetails();
                }

}

I have included all 4 methods in same class, However if you need every method ( function ) seperately, please do let me know in the comment section and I will provide code for individual functions.

Question (A)

1) int size;

double [] list = new double[size]

This declaration is Invalid. Since the size of double list[] is given as size which is a variable of type int with no value in it. Which means you trying to do this : double [] list =new double [NULL] which is wrong declaration

The Valid declaration for this is :

int size=10;

double [ ] list = new double [size];

2) int [ ] test = new int [-10];

This declaration is Invalid. We can not declare a array with negative size.

correct declaration is int [ ] test = new int [10];

3) double [ ] sales = new double [40.5];

This declaration is Invalid. Type of the array is double, that doest mean size has to be a doube value. It just mean the elements stored in that array will be of double data type. Size of the array should alway be of type "int".

Correct declaration : double [ ] sales = new double [40];

4) int x,y;

har[ ] [ ] board = new board [x][y];

This declaration is invalid. Because the syntax for declaring an array is data_type [ ] array_name = new data_type [size] . But the above declaration has no data type mentioned on valid size.

The correct declaration is:

int x=3;

int y=3;

int [ ] [ ] board = new int [x][y];

Hope this answer helps you.

Thank you :)