Currency Converter in Java

[Deepak Lal]

Hi Ranchers,
We are designing a java based application for currency conversion where the currency name and currency decode values are stored in Currency Table,The foreign exchange rates are stored in Foreign_exchange rates table.I have to go ahead and implement this,can you please suggest me some ideas as to how should i go about implementing this.This scenario is in Trading based real time application where the foreign exchange rates are changing every now and then,so my question is how will i get the latest value which will be in sync and calculate the "correct conversion rate".Please advice..What datastructure should i use for implementing this.

Currency Table
Currency name|Decode
Indian Rupee|INR

Foreign Exchange Rate(Example) table
CurrencyName|F_E_Name|F_E_Value
INR|USD|46
INR|EUR|56
INR|GBP|80
INR|Dinar|120 ... so on

The above values will be got from a foreign exchange feeder system,how will i ensure the values are in sync always?Hope my question is understood now.

Regards,
Deepak.

[Deepak Lal]

Hi Ranchers,
Please help me with this issue ?
Regards
Deepak

[Wouter Oet]

First of all remember that PatienceIsAVirtue. We are all volunteers that do this in our free time.

I use the java.util.Currency class and create a wrapper that contains the conversion values.
A simple Map would be sufficient. Or in a multi-threaded environment a ConcurrentMap.

[Deepak Lal]

Wouter Oet wrote:First of all remember that PatienceIsAVirtue. We are all volunteers that do this in our free time.

I use the java.util.Currency class and create a wrapper that contains the conversion values.
A simple Map would be sufficient. Or in a multi-threaded environment a ConcurrentMap.

Thanks for your time and reply,but i do not know as to how should i implement using the Currency class.How should i write a wrapper for conversion values either.Could you advice me on this.?

[Paul Clapham]

It seems that you might be getting the data from some database tables. In that case your first attempt at design should be to create classes which mirror those tables. Each column in a table should be implemented as a member of the class.

Why don't you start out with, say, your Currency table? Post the contents of the table (I mean the list of columns, not the data in the table) and a class you have written based on that. Then we can discuss it.

[Deepak Lal]

Paul Clapham wrote:It seems that you might be getting the data from some database tables. In that case your first attempt at design should be to create classes which mirror those tables. Each column in a table should be implemented as a member of the class.

Why don't you start out with, say, your Currency table? Post the contents of the table (I mean the list of columns, not the data in the table) and a class you have written based on that. Then we can discuss it.

@Paul,Please find the classes below

class currency{
  private int currencyPk;
  private String primaryCurrencyName;
  private String decode;
  //getter and setters for the same
}

class foreignExchangeRate{
     private int currencyFk;
     private String primaryCurrencyName;
     private String foreignExchangeCurrencyName;
     private int foreignExchangeCurrencyValue;
    //getter and setters for the same
}

The above 2 classes mirror my database tables...Please let me know if design is correct or not now..how should i proceed now.

[Paul Clapham]

Well, that answers your original question, which was (to remind everyone reading this thread):

Deepak Lal wrote:Please advice..What datastructure should i use for implementing this.

So yes, that's a reasonable data structure to use. Do you have another specific question? "How should I proceed now" isn't a specific question which can reasonably be answered on a forum, except by saying "Next you should decide what you want to do with those data structures."

[Deepak Lal]

Paul Clapham wrote:Well, that answers your original question, which was (to remind everyone reading this thread):

Deepak Lal wrote:Please advice..What datastructure should i use for implementing this.

So yes, that's a reasonable data structure to use. Do you have another specific question? "How should I proceed now" isn't a specific question which can reasonably be answered on a forum, except by saying "Next you should decide what you want to do with those data structures."

@Paul,I have written the data structure,so my next question is how should i implement the currency converter which i have been discussing in this thread.

[Paul Clapham]

Deepak Lal wrote:@Paul,I have written the data structure,so my next question is how should i implement the currency converter which i have been discussing in this thread.

Well, first you should decide what things you want it to do. Then you write code which does those things. So how about if you get started with that? List the things you want it to do.

[Deepak Lal]

Paul Clapham wrote:

Deepak Lal wrote:@Paul,I have written the data structure,so my next question is how should i implement the currency converter which i have been discussing in this thread.

Well, first you should decide what things you want it to do. Then you write code which does those things. So how about if you get started with that? List the things you want it to do.

As i mentioned it should convert the currency rates(as it has been discussed in the orginal post also.)suppose i have 1 USD equivalent to 46 INR hence if i enter 12 USD it should give me the quivalent INR and point ot remember here is that INR rate is changing per sec/nanosec since im working in a real time Trade based Java application.so this is what im supposed to do,hope you have got my understanding now.Could you please tell me how should my implementation code be for this.

[Campbell Ritchie]

Deepak Lal wrote: . . . Could you please tell me how should my implementation code be for this.

No. You may however be able to pay one of us to write it for you.

[Darryl Burke]

Please BeForthrightWhenCrossPostingToOtherSites
http://forums.oracle.com/forums/thread.jspa?threadID=1693488

[Deepak Lal]

@Darryl,Sorry for cross posting in other forums.I went out of my way to post in OTN forums.

[Paul Clapham]

Deepak Lal wrote:suppose i have 1 USD equivalent to 46 INR hence if i enter 12 USD it should give me the quivalent INR and point ot remember here is that INR rate is changing per sec/nanosec since im working in a real time Trade based Java application.so this is what im supposed to do,hope you have got my understanding now.Could you please tell me how should my implementation code be for this.

First you should figure out what your requirements are. Write them down in a list. Then implement them one at a time.

What you have posted there isn't a requirement. It's a mish-mash of two separate requirements, namely

The code should calculate the number of INR corresponding to a given number of USD.

The code should use the most recent available conversion rates.

Then once you have a list of requirements, you can focus on them separately. You can see from what you posted there that you can't think about doing an ordinary currency conversion because you started raving about nanoseconds. Just do one thing at a time.

And by the way, an example isn't a requirement. Working from examples is likely to lead to problems because the examples usually don't cover the whole requirement.

[Soumyajit Hazra]

INR rate is changing per sec/nanosec since im working in a real time Trade based Java application

Not sure but I think the exchange rate changed daily basis not every second. Please rectify me if I am incorrect.

[Campbell Ritchie]

It is not usual to detect changes by the nanosecond, but rates and share prices etc. can change from second to second.

[Deepak Lal]

Ranchers,
Please find the implementation below

----------------------------------------------------------------
Converter.java

import java.io.*;
import java.util.*;

class Converter {

  /* The Converter Program     
   * ------------------------------------------------------------
   * Keeps the exchange rates from one currency into
   * many others and enables currency exchanges to be
   * estimated.
   *
   * Illustrates the use of hash tables.
   */

  public static void main(String[] args) throws IOException {
      DataHandler data = new DataHandler ();
      data.initialise();
      data.readIn();
      data.echo();
      data.transactions();
  }
  
  static class DataHandler {
    Hashtable table = new Hashtable();
  
    // read in each line of data and store in
    // the hash table with country as key
    
    Rates rate;
    Display display = new Display ("Currency Converter");
    
    void initialise () {
      display.println("Currency Converter\n"+
                      "==================");
      display.prompt("Rates file", "rates.data");
      display.ready("Press ready when the file is ok");
    }
    
    void readIn() throws IOException {
      String filename = display.getString("Rates file");
      BufferedReader fin = Text.open(filename);
      try {
        for (int i = 0; ; i++) {
          rate = new Rates();
          rate.setRate(fin);
          table.put(rate.country, rate);
        }
      }
      catch (EOFException e) {
        display.println("Data read in and stored\n");
      }
    }
  
    void echo() {
      display.println("In the table");
      int i = 1;
      for (Enumeration e = table.keys(); e.hasMoreElements(); i++) {
        String country = (String)e.nextElement();
        display.println(country);
      }
    }
    
    void transactions () {
      display.prompt("Country", "American");
      display.prompt("Amount", 1000);
      String country;
      double amount;
      String c;
      Rates r;

      while (true) {
        display.println("Scroll up to see countries");
        display.ready("Enter country and amount and press ready");
        c = display.getString("Country");
        if (table.containsKey(c)) {
          amount = display.getDouble("Amount");
          r = (Rates) table.get(c);
          display.println(amount+" in "+c+" "
              +r.currency+" is "+
              Text.format(amount * r.conversion,6,2)+"\n");
        } else 
           display.println("Sorry, country "+c+" not in table\n");
      }
    }
  }
  
}
-----------------------------------------------------------------------------------
Rates.java

import java.io.*;

class Rates {
  /* The Rates class   
   * ---------------
   * Stores a country name, currency, code and rate 
   */

  String country;
  String code;
  String currency;
  double conversion;

  void setRate (BufferedReader in) throws IOException {
    code = Text.readString(in);
    country = Text.readString(in);
    currency = Text.readString(in);
    // ignore first rate by overwriting it
    conversion = Text.readDouble(in);
    conversion = Text.readDouble(in);
  }
  
 }

---------------------------------------------------------------------------------------------
rates.data(sample data file)

DZD Algerian Dinars                       0.0822               12.2 
USD American Dollars                      4.820                 0.2074 
ARP Argentinian Pesos                     4.822                 0.2074 
AUD Australian Dollars                    3.368                 0.2969 
ATS Austrian Schillings                   0.3982                2.511 
BSD Bahamian Dollars                      4.820                 0.2074 
BBD Barbados Dollars                      2.397                 0.4172 
BEF Belgian Francs                        0.1359                7.360 
BMD Bermudian Dollars                     4.820                 0.2074 
BRR Brazilian Real                        4.351                 0.2298 
GBP British Pounds                        8.162                 0.1225 
BGL Bulgarian Lev                         0.00282             355 
CAD Canadian Dollars                      3.439                 0.2908 
CLP Chilean Pesos                         0.01147              87.20 
CNY Chinese Renmimbi                      0.5822                1.718 
CYP Cyprus Pounds                         9.500                 0.1053 
CSK Czech Koruna                          0.147                 6.79 
DKK Danish Kroner                         0.7366                1.358 
NLG Dutch Guilders                        2.483                 0.4027 
XEC Eastern-Caribbean Units               1.785                 0.5601 
EGP Egyptian Pounds                       1.418                 0.7053 
XEU European-Currency Units               5.536                 0.1806 
FJD Fijian Dollars                        3.268                 0.3060 
FIM Finnish Markka                        0.9316                1.073 
FRF French Francs                         0.8377                1.194 
DEM German Marks                          2.803                 0.3568 
XAU Gold Ounces                           1504                     0.0006648 
GRD Greek Drachmas                        0.01781              56.14 
HKD Hong-Kong Dollars                     0.6235                1.604 
HUF Hungarian Forint                      0.0248               40.3 
ISK Icelandic Krona                       0.06798              14.71 
INR Indian Rupees                         0.1324                7.551 
IDR Indonesian Rupiah                     0.00148             676 
IEP Irish Punt                            7.292                 0.1371 
ILS Israeli New-Shekels                   1.370                 0.7301 
ITL Italian Lira                          0.00286             350 
JMD Jamaican Dollars                      0.1395                7.168 
JPY Japanese Yen                          0.03913              25.55 
JOD Jordanian Dinar                       6.808                 0.1469 
LBP Lebanese Pounds                       0.00314             319 
LUF Luxembourg Francs                     0.1359                7.360 
MYR Malaysian Ringgit                     1.465                 0.6825 
MXP Mexican New-Pesos                     0.5763                1.735 
NZD New-Zealand Dollars                   3.012                 0.3320 
NOK Norwegian Kroner                      0.6881                1.453 
PKR Pakistani Rupees                      0.1095                9.130 
PHP Philippines Pesos                     0.1393                7.178 
XPT Platinum Ounces                       1904                     0.0005252 
PLZ Polish Zloty                          1.388                 0.7205 
PTE Portugese Escudo                      0.0274               36.4 
ROL Romanian Leu                          0.000619           1620 
SUR Russian Rubles                        0.0008160          1225 
SAR Saudi-Arabian Riyal                   1.285                 0.7780 
XAG Silver Ounces                         23.40                  0.04273 
SGD Singapore Dollars                     3.066                 0.3261 
SKK Slovakian Koruna                      0.144                 6.94 
ZAR South-African Rand                    1.000                 1.000 
KRW South-Korean Won                      0.004945            202.2 
ESP Spanish Pesetas                       0.0332               30.1 
SDD Sudanese Dinar                        0.0292               34.2 
SEK Swedish Krona                         0.6437                1.553 
CHF Swiss Francs                          3.428                 0.2917 
TWD Taiwan Dollars                        0.1580                6.327 
THB Thai Baht                             0.123                 8.12 
TTD Trinidad-and-Tobago Dollars           0.7799                1.282 
TRL Turkish Lira                          0.000026          38000 
VEB Venezuelan Bolivar                    0.009670            103.4 
ZMK Zambian Kwacha                        0.003611            277.0 

-----------------------------------------------------------------------------------------------------------------------------------------------------------------
Hi Campbell,Im using a static rates.data file for currency rates to be loaded ,can you tell me how to make it dynamic so that
i get the latest currency rates in this setup,sorry for the usage of nanasecond,we would say the currency are changing at the rate per second.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------

Best Regards
Deepak Lal