Chapter 6 Computer Programming - Methods

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[Please answer Task 2 & 4 with the missing code under the bolded sections]

Code Listing 5.1 (Geometry.java)

import java.util.Scanner;

/** This program demonstrates static methods */

public class Geometry { public static void main(String[] args) { int choice; // The user's choice double value = 0; // The method's return value char letter; // The user's Y or N decision double radius; // The radius of the circle double length; // The length of the rectangle double width; // The width of the rectangle double height; // The height of the triangle double base; // The base of the triangle double side1; // The first side of the triangle double side2; // The second side of the triangle double side3; // The third side of the triangle

// Create a scanner object to read from the keyboard Scanner keyboard = new Scanner(System.in);

// The do loop allows the menu to be displayed first do { // TASK #1 Call the printMenu method

choice = keyboard.nextInt();

switch (choice)

{ case 1: System.out.print("Enter the radius of " + "the circle: "); radius = keyboard.nextDouble();

// TASK #3 Call the circleArea method and // store the result in the value variable

System.out.println("The area of the " + "circle is " + value); break;

case 2: System.out.print("Enter the length of " + "the rectangle: "); length = keyboard.nextDouble(); System.out.print("Enter the width of " + "the rectangle: "); width = keyboard.nextDouble();

// TASK #3 Call the rectangleArea method and // store the result in the value variable

System.out.println("The area of the " + "rectangle is " + value); break;

case 3: System.out.print("Enter the height of " + "the triangle: "); height = keyboard.nextDouble(); System.out.print("Enter the base of " + "the triangle: "); base = keyboard.nextDouble();

// TASK #3 Call the triangleArea method and // store the result in the value variable

System.out.println("The area of the " + "triangle is " + value); break;

case 4: System.out.print("Enter the radius of " + "the circle: "); radius = keyboard.nextDouble(); // TASK #3 Call the circumference method and // store the result in the value variable

System.out.println("The circumference " + "of the circle is " + value); break;

case 5: System.out.print("Enter the length of " + "the rectangle: "); length = keyboard.nextDouble(); System.out.print("Enter the width of " + "the rectangle: "); width = keyboard.nextDouble();

// TASK #3 Call the perimeter method and // store the result in the value variable

System.out.println("The perimeter of " + "the rectangle is " + value); break;

case 6: System.out.print("Enter the length of " + "side 1 of the " + "triangle: "); side1 = keyboard.nextDouble(); System.out.print("Enter the length of " + "side 2 of the " + "triangle: "); side2 = keyboard.nextDouble(); System.out.print("Enter the length of " + "side 3 of the " + "triangle: "); side3 = keyboard.nextDouble();

// TASK #3 Call the perimeter method and // store the result in the value variable

System.out.println("The perimeter of " + "the triangle is " + value); break; default: System.out.println("You did not enter " + "a valid choice."); }

keyboard.nextLine(); // Consume the new line

System.out.println("Do you want to exit " + "the program (Y/N)?: "); String answer = keyboard.nextLine(); letter = answer.charAt(0);

} while(letter != 'Y' && letter != 'y'); }

// TASK #1 Create the printMenu method here // TASK #2 Create the value-returning methods here // TASK #4 Write javadoc comments for each method }

Task #2 Value-Returning Methods 1. Write a static method called circleArea that takes in the radius of the circle and returns the area using the formula A = r 2 2. Write a static method called rectangleArea that takes in the length and width of the rectangle and returns the area using the formula A = M. 3. Write a static method called triangleArea that takes in the base and height of the triangle and returns the area using the formula A = bh. 4. Write a static method called circleCircunference that takes in the radius of the circle and returns the circumference using the formula C = 2w. 5. Write a static method called rectanglePerimeter that takes in the length and the width of the rectangle and returns the perimeter of the rectangle using the formula P 21 +2w. 6. Write a static method called trianglePerimeter that takes in the lengths of the three sides of the triangle and returns the perimeter of the triangle which is calculated by adding up the three sides