Chapter 3 Java

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import java.util.Scanner;

public class RomanNumerals {

    public static void main(String[] args) {
        //Define variables
        String userInput;
        int input;
        String romanNumeral;
        //user input
        System.out.print("Enter a number in the range of 1 - 10: ");
        Scanner keyboard = new Scanner(System.in);
        userInput = keyboard.nextLine();
        input = Integer.parseInt(userInput);
        switch (input) {
            case 1:  romanNumeral = "I";
                break;
            case 2:  romanNumeral = "II";
                break;
            case 3:  romanNumeral = "III";
                break;
            case 4:  romanNumeral = "IV";
                break;
            case 5:  romanNumeral = "V";
                break;
            case 6:  romanNumeral = "VI";
                break;
            case 7:  romanNumeral = "VII";
                break;
            case 8:  romanNumeral = "VIII";
                break;
            case 9:  romanNumeral = "IX";
                break;
            case 10:  romanNumeral = "X";
                break;
            default: romanNumeral = "";
                break;
        }
        System.out.print(romanNumeral);
    }
}

import java.util.*;
import java.text.*;

public class SoftwareSales {

    public static void main(String[] args){
           double discount, priceDiscount, price;
        System.out.print("Enter number of packages purchased:");
        Scanner keyboard = new Scanner(System.in);
        int quantity = keyboard.nextInt();
        price = 99* quantity;
        if (quantity >= 10 && quantity <=19){discount = price * .2; priceDiscount = price - discount;}
        else if (quantity >= 20 && quantity <=49){discount = price * .3; priceDiscount = price - discount;}
        else if (quantity >= 50 && quantity <=99){discount = price * .4; priceDiscount = price - discount;}
        else if (quantity >=100){discount = price * .5; priceDiscount = price - discount;}
        else { discount = 0; priceDiscount=price;}
        DecimalFormat dFormat = new DecimalFormat("0.00");
        System.out.println(" Your discount is: $"+ dFormat.format(discount));
        System.out.println("Your total is: $" + dFormat.format(priceDiscount));
    }
}

import java.util.Scanner;

public class Runners {

    public static void main(String[] args) {
        // Basic i/o

        Scanner keyboard = new Scanner(System.in);
        System.out.print("Enter runner 1 name:");
        String runner1 = keyboard.nextLine();
        System.out.print(" Enter runner 1 time (in minutes):");
        int time1 = keyboard.nextInt();
        keyboard.nextLine();
        System.out.print(" Enter runner 2 name:");
        String runner2 = keyboard.nextLine();
        System.out.print(" Enter runner 2 time (in minutes):");
        int time2 = keyboard.nextInt();
        keyboard.nextLine();
        System.out.print(" Enter runner 3 name:");
        String runner3 = keyboard.nextLine();
        System.out.print(" Enter runner 3 time (in minutes):");
        int time3 = keyboard.nextInt();

        if (time1 < time2 && time1<time3){
            System.out.println(" "+runner1);
            if(time2<time3){
                System.out.println(runner2);
                System.out.println(runner3);
            } else{
                System.out.println(runner2);
                System.out.println(runner3);
            }
        } else if (time2 < time1 && time2<time3){
            System.out.println(" "+runner2);
            if(time1<time3){
                System.out.println(runner1);
                System.out.println(runner3);
            }else{
                System.out.println(runner3);
                System.out.println(runner1);
            }
        } else if (time3<time1 && time3<time2){
            System.out.println(" "+runner3);
            if(time1<time2){
                System.out.println(runner1);
                System.out.println(runner2);
            }else{
                System.out.println(runner2);
                System.out.println(runner1);
            }
        } else{
            System.out.println(" "+runner1);
            System.out.println(runner2);
            System.out.println(runner3);
        }
    }
}

import java.util.Scanner;
import javax.swing.JOptionPane;
//import java.io.*;
//import java.util.Random;

public class TheSpeedOfSound {

    public static void main(String[] args)  {
        //define variables
        String medium;
        String distanceInput;
        double distance;
        double travelTime;
        final String userMediumPrompt = "Enter one of the following: air, water, or steel: ";
        final String userDistancePrompt = "Enter the distance the sound wave will travel: ";
        final String userError = "Sorry, you must enter air, water, or steel.";
        final String air = "air";
        final String water = "water";
        final String steel = "steel";
        // User input
        System.out.print(userMediumPrompt);
        Scanner keyboard = new Scanner(System.in);
        medium = keyboard.nextLine();
        //////////////////////
        //calculate traveltime
        //////////////////////

        if (medium.equals(air)){
            //Prompt for distance
            System.out.print(userDistancePrompt);
            distanceInput = keyboard.nextLine();
            distance = Double.parseDouble(distanceInput);
            //calculate travelTime
            travelTime = distance/1100;
            //output travelTime
            System.out.print(" It will take " + travelTime + " seconds.");

        }
        else if (medium.equals(water)){
            //Prompt for distance
            System.out.print(userDistancePrompt);
            distanceInput = keyboard.nextLine();
            distance = Double.parseDouble(distanceInput);
            //calculate travelTime
            travelTime = distance/4900;
            //output travelTime
            System.out.println(" It will take " + travelTime + " seconds.");
        }
        else if (medium.equals(steel)){
            //Prompt for distance
            System.out.print(userDistancePrompt);
            distanceInput = keyboard.nextLine();
            distance = Double.parseDouble(distanceInput);
            //calculate travelTime
            travelTime = distance/16400;
            //output travelTime
            System.out.print(" It will take " + travelTime + " seconds.");
        }
        else {
            //Output error
            System.out.print(userError);
        }


    }
}