CurrencyConversion.java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package currencyconversion;
import java.util.Scanner;

/**
 *
 * @author maf946
 */
public class CurrencyConversion {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
//        Currency conversion: Write a snippet that first asks the user to type
//            today's U.S. dollar price for one Bitcoin. Then use a loop to:
//                1. prompt the user to enter a Bitcoin quantity
//                2. convert that amount to US dollars
//                3. print the amount to the screen, formatted to two decimal places  
//        Use "stop" as a sentinel to stop the loop.
        double dollarPrice;
        double bitcoinAmount;
        double conversionPrice;
               
        Scanner scnr = new Scanner(System.in);
        System.out.print("Enter today's U.S. dollar price for one Bitcoin (ex: 999.99): ");
        dollarPrice = scnr.nextDouble();
        
        while (true) {
            System.out.print("Please enter a Bitcoin quantity (ex: 1.23), or \"stop\" to stop: ");
            if (scnr.hasNextDouble()) {
                bitcoinAmount = scnr.nextDouble();
                conversionPrice = dollarPrice * bitcoinAmount;
                System.out.print(bitcoinAmount + " Bitcoin equals $");
                System.out.printf("%.2f", conversionPrice);
                System.out.print("\n");  
            } else {
                if (scnr.next().equals("stop")) {
                    break;
                } else {
                    System.out.println("Invalid input!");
                }
            }
        }    
    }
}