How to write Simple Currency Converter using Java Program

on December 1, 2016

Post Views: 2,373

Simple Currency Converter using Java

In this example, I am attaching simple program about, How to write Simple Currency Converter using Java Program. The program was written using Fixer Currency Converter Webservice.

Project Structure

Simple Currency Converter using Java

Note : In this example, I am using Gson 2.8.0 API to convert JSON to Object in Java. you can download API from here

CurrencyConversionResponse.java

package com.javatraineronline;
import java.util.Map;
import java.util.TreeMap;
/**
* 
* @author Dinesh Krishnan
*
*/
public class CurrencyConversionResponse {
private String base;
private String date;
private Map<String, String> rates = new TreeMap<String, String>();
public Map<String, String> getRates() {
return rates;
}
public void setRates(Map<String, String> rates) {
this.rates = rates;
}
public String getBase() {
return base;
}
public void setBase(String base) {
this.base = base;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
}

CurrencyConvertor.java

package com.javatraineronline;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Scanner;
import com.google.gson.Gson;
/**
* 
* @author Dinesh Krishnan
*
*/
public class CurrencyConvertor {
// API Provider URL
private static final String API_PROVDIER = "http://api.fixer.io/";
public static double convert(String fromCurrencyCode, String toCurrencyCode) {
if ((fromCurrencyCode != null && !fromCurrencyCode.isEmpty())
&& (toCurrencyCode != null && !toCurrencyCode.isEmpty())) {
CurrencyConversionResponse response = getResponse(API_PROVDIER+"/latest?base="+fromCurrencyCode);
if(response != null) {
String rate = response.getRates().get(toCurrencyCode);
double conversionRate = Double.valueOf((rate != null)?rate:"0.0");
return conversionRate;
}
}
return 0.0;
}
// Method to get the response from API
private static CurrencyConversionResponse getResponse(String strUrl) {
CurrencyConversionResponse response = null;
Gson gson = new Gson();
StringBuffer sb = new StringBuffer();
if(strUrl == null || strUrl.isEmpty()) {
System.out.println("Application Error");
return null;
}
URL url;
try {
url = new URL(strUrl);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
InputStream stream = connection.getInputStream();
int data = stream.read();
while (data != -1) {
sb.append((char) data);
data = stream.read();
}
stream.close();
response = gson.fromJson(sb.toString(), CurrencyConversionResponse.class);
} catch (MalformedURLException e) {
System.out.println(e.getMessage());
e.printStackTrace();
} catch (IOException e) {
System.out.println(e.getMessage());
e.printStackTrace();
}
return response;
}
public static void main(String[] args) throws IOException {
Scanner scanner = new Scanner(System.in);
System.out.println("What is your currency code ?");
String fromCurrencyCode = scanner.next();
System.out.println("Enter the Amount :");
double amount = scanner.nextDouble();
System.out.println("Enter the Currency Code that you want to covert : ");
String toCurrencyCode = scanner.next();
fromCurrencyCode = fromCurrencyCode.toUpperCase();
toCurrencyCode = toCurrencyCode.toUpperCase();
// Currency Conversion
double coversionRate = convert(fromCurrencyCode, toCurrencyCode);
System.out.println("Hi, The "+amount +" "+ fromCurrencyCode+" is equivalent to "+(coversionRate * amount)+" "+toCurrencyCode+" today.");
scanner.close();
}
}

Output

What is your currency code ?
USD
Enter the Amount :
600
Enter the Currency Code that you want to covert :
INR
Hi, The 600.0 USD is equivalent to 41105.4 INR today.