Question

Create a program called Currency Conversion. This will convert one currency to other currencies (for example CAD to GBP, Euro and USD).  The program should prompt user to choose currency in hand and currency required. It should also ask the user to enter amount (currency value).  The conversion rate is fixed as mentioned below. You should store the exchange rate as final values.  Use Scanner for input and printf for formatting decimals (rounded to two decimal places)  Add comments for wherever needed for code maintenance and mathematical procedures  Your program should display well-articulated print statement with appropriate symbols. Exchange rate: As most of the currencies are traded against USD, the exchange rates are expressed in US dollars. One Euro (€) = 1.124 US dollar One CAD ($) = 0.758US dollars One GBP (£) = 1.296 US dollar

Programming Guidelines:  Beginning comments: Include your name and a short narrative as a comment at the beginning of your program stating what the program does, not how it does it.  Ensure variable names are meaningful. Use lower CamelCase. Do not use made up short forms for any part of a variable name.  Are brace brackets aligned? The opening brace bracket should be in the same column as the closing bracket. Did you indent inside the brace bracket?  Challenge: Validate user inputs to ensure it’s not inappropriate, negative entry or zero. Allow the user to re- enter invalid data.  Is the output informative and formatted properly? Use currency symbol and 2 decimal places. Output is well spaced not too congested. Include the blank lines to separate the outputs.  Ensure that the file you submitted can be opened successfully.  Ensure you do not get a divide by zero error when converting currency.

Answer 1

/**
* CurrencyConverter class
* The program prompt the user to choose currency in hand and currency required.
* It also ask the user to enter amount (currency value)
* Then displays the exchange value
* This program validates every inputs for currency
* Only the positive value for the amount is accepted
*/
import java.util.Scanner;
public class CurrencyConverter {
    // final variables for exchange rate of each currency
    static final double EURO = 1.124;
    static final double CAD = 0.758;
    static final double GBP = 1.296;
    // main method
    public static void main(String[] args) {
        // scnnaer object to read input
        Scanner in = new Scanner(System.in);
        // variable for currency in hand
        String currencyFrom;
        // loop to get and validate input for currency in hand
        while(true){
            System.out.print("Enter currency in hand: ");
            currencyFrom = in.next().toUpperCase();
            if(checkCurrency(currencyFrom))
                break;
            System.out.println("Invalid currency");
        }
      
        // variable for currency required
        String currencyTo;
        // loop to get and validate input for currency required
        while(true){
            System.out.print("Enter required currency: ");
            currencyTo = in.next().toUpperCase();
            if(checkCurrency(currencyTo))
                break;
            System.out.println("Invalid currency");
        }
      
        // variable for amount
        double amount;
        // loop to get positive value for the amount
        while(true){
            System.out.print("Enter Amount: ");
            amount = in.nextDouble();
            if(amount>0)
                break;
            System.out.println("Invalid amount");
        }
      
        // convert given amount to dollar from currency in hand
        double dollar = convertToDollar(currencyFrom, amount);
        // convert dollar to required currency
        double exchangeValue = dollarToCurrency(currencyTo, dollar);
        // display the amount and exchange value in 2 decimal places
        System.out.printf("\n%.2f %s = %.2f %s\n",amount,currencyFrom,exchangeValue,currencyTo);
      
    }
  
    // method to convert given currency amount to dollar
    private static double convertToDollar(String currencyFrom, double value) {
        if(currencyFrom.equals("EURO"))
            return value*EURO;
        if(currencyFrom.equals("CAD"))
            return value*CAD;
        if(currencyFrom.equals("GBP"))
            return value*GBP;
        if(currencyFrom.equals("USD"))
            return value;
        return 0.0;
    }

    // method to convert dollar to given currency amount
    private static double dollarToCurrency(String currency, double dollar) {
        if(currency.equals("EURO"))
            return dollar/EURO;
        if(currency.equals("CAD"))
            return dollar/CAD;
        if(currency.equals("GBP"))
            return dollar/GBP;
        if(currency.equals("USD"))
            return dollar;
        return 0.0;
    }

    // method to check currency
    private static boolean checkCurrency(String currency) {
        return currency.equals("USD") || currency.equals("CAD") || currency.equals("EURO") ||currency.equals("GBP");
    }
}

Sample output