Week 5 Homework Solutions

WeekFiveHW.java

import java.util.Scanner;

/**
 * This class contains the solutions to
 * the Week 5 homework exercises.
 */
public class WeekFiveHW {

    public static void main(String[] args) {

        // Mandatory Problem 1
        System.out.println("\nMandatory Problem 1\n"); // to separate problems

        double s = 6.3; // change numbers to see what happens
        double r = 2.5;
        double h = 5.0;

        // calling each method and storing volumes in variables
        double vol1 = sphereVolume(r);
        double vol2 = cubeVolume(s);
        double vol3 = coneVolume(r, h);

        // printing volumes
        System.out.println("\t" + "Sphere volume is " + vol1);
        System.out.println("\t" + "Cube volume is " + vol2);
        System.out.println("\t" + "Cone volume is " + vol3);

        // Mandatory Problem 2
        System.out.println("\nMandatory Problem 2\n"); // to separate problems
        guessFruit("orange");

        // Optional Problem 1
        System.out.println("\nOptional Problem 1\n"); // to separate problems
        System.out.println("\tDistance: " + getDistance(4.5, 9.0, 8.3, 1.7));

    }

    /* Mandatory Problem 1: Volumes
    - Create three methods: sphereVolume(), cubeVolume(), and coneVolume() that
    calculate and return the volume of a sphere, cube, and cone
        - sphereVolume() should have 1 parameter (the radius)
        - cubeVolume() should have 1 parameter (the side length)
        - coneVolume() should have 2 parameters (the radius and height)
        - Each method should use one or more Math class methods
     */

    // sphereVolume() method
    public static double sphereVolume(double radius) {
        return (4.0/3.0) * Math.PI * Math.pow(radius, 3.0);
    }

    // cubeVolume() method
    public static double cubeVolume(double side_length) {
        return Math.pow(side_length, 3.0);
    }

    // coneVolume() method
    public static double coneVolume(double radius, double height) {
        return (1.0/3.0) * Math.PI * Math.pow(radius, 2.0) * height;
    }


    /* Mandatory Problem 2: Guess the Fruit
    - Create a method called guessFruit() that returns void (null) that:
        - Takes in String input from the user
        - User must guess the correct fruit
        - While the guess does not equal the correct fruit, the program should
          keep asking the user to guess a fruit
        - If the user input equals the correct answer, the program should print
          “You guessed the right fruit!”
        - Should use one or more String methods
    - Hint: You should use a while loop! And the “!=” operator will NOT
      work in this problem
    */

    // guessFruit method
    public static void guessFruit(String fruit) {

        Scanner userInput = new Scanner(System.in); // create scanner object
        System.out.println("\tGuess the fruit!"); // ask user question
        String guess = userInput.nextLine(); // get input from user

        // while guess is not equal to correct fruit
        while(!guess.equals(fruit)) {
            System.out.println("\tSorry, try again: ");
            guess = userInput.nextLine();
        }

        // congratulate user on guessing the fruit
        System.out.println("\tYay! You guessed the right fruit!");
        userInput.close();

    }

    /* Optional Problem 1: Get Distance
    - Create a method called getDistance that calculates the
      distance between any two points in a coordinate plane
        - It should have 4 parameters
        - It should return the distance
        - It should use one or more Math class methods
     */

    // getDistance() method
    public static double getDistance(double x1, double y1, double x2, double y2) {

        // get delta x and delta y
        double dx_squared = Math.pow((x2 - x1), 2);
        double dy_squared = Math.pow((y2 - y1), 2);

        return Math.sqrt(dx_squared + dy_squared);
    }

}