JavaMoney is the new monetary API for the Java™ Platform as well as related projects and libraries. Whereas the API (JSR 354) provides a portable and extendible API for handling of Money & Currency models, Moneta provides a production ready reference implementation. The JavaMoney libraries add additional functionalities that were built on top of the API such as - Basic financial operations - Rounding - Currency conversion - Extended formatting (usable for arbitrary types)

1. JSR 354: Money and Currency API
Werner Keil | Otávio Santana
@wernerkeil | @otaviojava | @jsr354
https://www.jcp.org/en/jsr/detail?id=354
http://javamoney.org

2. History and Motivation

3. Earlier Approaches
Martin Fowler:
A large proportion of the computers in this
world manipulate money, so it’s always
puzzled me that money isn’t actually a first
class data type in any mainstream
programming language. The lack of a type
causes problems, the most obvious
surrounding currencies…
see
http://martinfowler.com/eaaCatalog/money.html
Eric Evans – Time and Money:
On project after project, software developers have
to reinvent the wheel, creating objects for simple
recurring concepts such as “money” and
“currency”. Although most languages have a
“date” or “time” object, these are rudimentary, and
do not cover many needs, such as recurring
sequences of time, durations of time, or intervals
of time. …
To be quite frank, their code isn’t more than an
academic POC, factories called dollars() or
euros() are useless in real globally deployed
frameworks, but he made a good point.

4. Motivation
> Monetary values are a key feature to many applications
> Existing java.util.Currency class is strictly a structure used for representing
ISO-4217 standard currencies.
> No standard value type to represent a monetary amount
> No support for currency arithmetic or conversion
> JDK Formatting features lack flexibility

5. Overview of JSR 354
> Core API: javax.money
 CurrencyUnit, MonetaryAmount
> Conversion API: javax.money.convert
 ExchangeRate, ConversionContext
> Formatting: javax.money.format
 AmountFormatContext, MonetaryAmountFormat
> Reference Implementation: org.javamoney.moneta
> TCK: org.javamoney.tck

6. /**
* Simplest case create an amount with an ISO currency.
*/
public void forISOCurrencies() {
Money amount = Money.of(1234566.15, "USD"); // using ISO namespace by default
}
/**
* Create an amount using a custom currency.
*/
public void forCustomCurrencies() {
CurrencyUnit currency = Monetary.getCurrency("myCode");
Money amount = Money.of(1234566.15, currency);
}
6 © 2012-2015 JavaMoney contributors
Creating Amounts

7. Currency Conversion
> ExchangeRateType
> ExchangeRate:
– ConversionContext
– Base, Term currency
– Conversion factor
– Direct/Derived Rates
> ConversionProvider/CurrencyConverter
> MonetaryConversions accessor singleton
public interface ExchangeRate {
public CurrencyUnit getBaseCurrency();
public CurrencyUnit getCurrency();
public NumberValue getFactor();
public ConversionContext getContext();
public List<ExchangeRate> getExchangeRateChain();
public boolean isDerived();
}
7 © 2012-2015 JavaMoney contributors

8. // Shows accessing exchange rates and doing conversions.
MonetaryAmount amt = Money.of(2000, "EUR");
System.out.println("2000 EUR -(ECB)-> HUF = " +
amt.with(MonetaryConversions.getConversion("HUF", "ECB")));
System.out.println("2000 EUR -(IMF)-> HUF = " +
amt.with(MonetaryConversions.getConversion("HUF", "IMF")));
System.out.println("2000 EUR -(ECB, at 5th Jan 2015)->
HUF = " +
amt.with(MonetaryConversions.getConversion(ConversionQueryBu
ilder.of().setTermCurrency("HUF")
.set(LocalDate.of(2015, 01, 05)).build())));
8 © 2012-2015 JavaMoney contributors
Currency Conversion

9. Virtual Currencies
> Video Game Currencies (Gold, Gil, Rupees, Credits, Gold Rings, Hearts, Zenny,
Potch, Munny, Nuyen…)
> Facebook Credits are a virtual currency you can use to buy
virtual goods in any games or apps of the Facebook
platform that accept payments. You can purchase
Facebook Credits directly from within an app using your
credit card, PayPal, mobile phone and many other local
payment methods.
> Bitcoin (sign: BTC) is a decentralized digital currency
based on an open-source, peer-to-peer internet protocol.
It was introduced by a pseudonymous developer named
Satoshi Nakamoto (allegedly Australian tech entrepreneur
Craig Wright) in 2009.

10. Adopters
Zalando
10 © 2012-2015 JavaMoney contributors
Image: Zalando

11. Gimme Shelter
Adopt-a-JSR and similar Efforts
11 © 2012-2015 JavaMoney contributors

12. Links
• JSR 354: https://jcp.org/en/jsr/detail?id=354
• JavaMoney Site: http://javamoney.org
• JavaMoney Shelter: http://javamoney.github.io/shelter.html
• GitHub Organization: https://github.com/JavaMoney/
• Twitter: @jsr354

13. Demo
javax.money