Instructions
Objective
Write a java assignment program to build foreign currency and perfect change.
Requirements and Specifications
At present, you have decided only to trade in the following currencies: GBP (British Pounds), EUR (Common Market Euros), and JPY (Japanese Yen). When it starts, your program will ask for the current exchange rates, after which it will begin a ‘valuation loop’ that lets you select the currency type and then enter the amount of that currency, whereupon the program tells you how much that would be in US dollars. A sample run would look like this (items in bold are user inputs):
In this program (closely related to the MakeChange calculator done previously) you will make change for a dollar from a specific number of available coins. To do this, a method that runs at the beginning will ask the user for a specific set of coins to use. Note that in part B, you will incorporate the MakeChange algorithm by making the choice of using a coinset an option.
Source Code
FOREIGN CURRENCY
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Scanner;
public class ForeignCurrency {
enum Currency {
EUR("Euros"),
GBP("Pounds Sterling"),
JPY("Yen"),
CAD("Canadian dollars"),
RUB("Russian Rubles");
private final String fullName;
Currency(String fullName) {
this.fullName = fullName;
}
public String getFullName() {
return fullName;
}
}
private static Map rate = new HashMap<>();
private static Map units = new HashMap<>();
private static Map prices = new HashMap<>();
private static double total = 0.0;
private static void readRates(Scanner scanner) {
System.out.println("Please enter the currency rate Per US $ of the following currencies:");
System.out.println();
for (Currency c : Currency.values()) {
System.out.print(c.toString() + ": ");
double d = Double.parseDouble(scanner.nextLine());
rate.put(c, d);
}
System.out.println();
}
private static int processChoice(Scanner scanner) {
System.out.print("Currency for valuation (1=EUR, 2=GBP, 3=JPY, 4=CAD, 5=RUB, 9=New Rates, 0=Quit): ");
int choice = Integer.parseInt(scanner.nextLine());
Currency c = null;
switch (choice) {
case 1:
c = Currency.EUR;
break;
case 2:
c = Currency.GBP;
break;
case 3:
c = Currency.JPY;
break;
case 4:
c = Currency.CAD;
break;
case 5:
c = Currency.RUB;
break;
}
if (c != null) {
System.out.print("How many " + c.getFullName() + " are you buying? ");
int value = Integer.parseInt(scanner.nextLine());
System.out.println();
double price = value * rate.get(c);
units.merge(c, value, Integer::sum);
prices.merge(c, price, (a,b) -> a+b);
total += price;
System.out.println("That will have a current value of $ " + String.format("%,.2f", price));
}
System.out.println();
return choice;
}
public static void main(String[] args) {
Locale.setDefault(Locale.US);
try (Scanner scanner = new Scanner(System.in)) {
System.out.println("Welcome to the currency calculator!");
System.out.println();
boolean isOver = false;
while (!isOver) {
readRates(scanner);
boolean newRates = false;
while (!newRates) {
int choice = processChoice(scanner);
if (choice == 9) {
newRates = true;
}
else if (choice == 0) {
newRates = true;
isOver = true;
}
}
}
for(Currency c : Currency.values()) {
int unit = units.getOrDefault(c, 0);
double price = prices.getOrDefault(c, 0.0);
System.out.println("\t" + c + ": " + unit + " units costing $" + String.format("%,.2f", price));
}
System.out.println("The total value of the proposed currency purchases was: $" + String.format("%,.2f", total));
System.out.println();
System.out.println("Thanks for using the currency calculator!");
}
}
}
PERFECT CHANGE
import java.util.Arrays;
import java.util.Scanner;
public class PerfectChange {
private static final int MAX_VALUE = 100;
private static final int[] VALUES = {25, 10, 5, 1};
private static int[][] solve(int[] counts) {
int[][][] A = new int[5][MAX_VALUE + 1][];
for (int i = 0; i < MAX_VALUE + 1; i++) {
if (i == 0) {
A[0][i] = new int[]{0, 0, 0, 0};
} else {
A[0][i] = null;
}
}
for (int i = 1; i < 5; i++) {
for (int j = 0; j < MAX_VALUE + 1; j++) {
if (A[i - 1][j] != null) {
A[i][j] = Arrays.copyOf(A[i - 1][j], 4);
} else {
for (int k = 1; k <= counts[i - 1]; k++) {
if (j - k * VALUES[i - 1] >= 0 && A[i - 1][j - k * VALUES[i - 1]] != null) {
A[i][j] = Arrays.copyOf(A[i - 1][j - k * VALUES[i - 1]], 4);
A[i][j][i - 1] += k;
break;
}
}
}
}
}
return A[4];
}
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
System.out.println("Welcome to the Perfect Change Calculator!");
System.out.println();
boolean isOver = false;
while (!isOver) {
System.out.print("Do you have a set of coins for making change? (Y/N): ");
boolean coinset = scanner.nextLine().trim().toUpperCase().equals("Y");
int quarters = 4;
int dimes = 10;
int nickels = 20;
int pennies = 1000;
if (coinset) {
System.out.println();
System.out.print("No of Quarters: ");
quarters = Integer.parseInt(scanner.nextLine());
System.out.print("No of Dimes: ");
dimes = Integer.parseInt(scanner.nextLine());
System.out.print("No of Nickels: ");
nickels = Integer.parseInt(scanner.nextLine());
System.out.print("No of Pennies: ");
pennies = Integer.parseInt(scanner.nextLine());
}
int[][] solution = solve(new int[]{quarters, dimes, nickels, pennies});
System.out.println();
boolean newCoinSet = false;
while (!newCoinSet) {
System.out.print("What value would you like change for? (1-100 cents, 101=New Coin set, 102=all values or 0=quit): ");
int value = Integer.parseInt(scanner.nextLine());
if (value <= 0) {
newCoinSet = true;
isOver = true;
} else if (value == 101) {
newCoinSet = true;
} else if (value > 101) {
for (int i = 0; i <= MAX_VALUE; i++) {
int[] sol = solution[i];
if (sol != null) {
System.out.print("For " + i + " cent(s) I give: ");
System.out.println(sol[0] + " quarters, " + sol[1] + " dimes, " + sol[2] + " nickels, " + sol[3] + " pennies");
} else {
int j = 1;
while (solution[i - j] == null) {
j++;
}
System.out.println("I could not make change for: " + i + " cents (I am short: " + j + " cents)");
}
}
} else {
int[] sol = solution[value];
if (sol == null) {
int i = 1;
while (solution[value - i] == null) {
i++;
}
System.out.println("I could not make change for: " + value + " cents (I am short: " + i + " cents)");
} else {
System.out.print("For " + value + " cent(s) I give:");
if (coinset) {
System.out.println();
System.out.print("\t");
} else {
System.out.print(" ");
}
System.out.print(sol[0] + " quarters, " + sol[1] + " dimes, " + sol[2] + " nickels, " + sol[3] + " pennies");
if (coinset) {
System.out.print(" leaving");
}
System.out.println();
if (coinset) {
System.out.println("\t" + (quarters - sol[0]) + " quarters, " + (dimes - sol[1]) + " dimes, " + (nickels - sol[2]) + " nickels, " + (pennies - sol[3]) + " pennies ");
}
}
}
System.out.println();
}
}
System.out.println("Thanks for using Perfect Change calculator!");
}
}
}