Go for the Money! JSR-354 @ JFS 2017

July 6, 2017 @ JFS 2017

**In the last years the development of the Java language itself is going on more rapidly and some long-awaited features were implemented. The best-known are the new *Date & Time API* and *Lambdas & Streams*. Specially for business applications there was another very interesting feature released in May 2015: JSR-354 – Money and Currency API**

What is this JSR about, why is there a need for a Money and Currency API? After answering these questions I provide an overview about the new API, their packages and classes with usage examples. I show how to calculate with money objects, how to convert between currencies, how to format and how to parse values using the Money and Currency API.

The Money and Currency API is compatible with Java 8 and newer. At the end of my talk there is a demonstration, where I show how an application can use the new Money and Currency API in practice. To fully understand this talk the attendees should have basic knowledge of Java.

Transcript

1. Go for the Money! JSR-354 A quick introduction to the Java Money and Currency API Marcus Fihlon July 6, 2017 Scrum Master | Software Engineer | Lecturer | Speaker | Author
2. Disclaimer The following presentation has been approved for open audiences only. Hypersensitivity to occasional profanity requires covering ears. All logos, photos etc. used in this presentation are the property of their respective copyright owners and are used here for educational purposes only. Any and all marks used throughout this presentation are trademarks of their respective owners. The presenter is not acting on behalf of CSS Insurance, neither as an official agent nor representative. The views expressed are those solely of the presenter. Marcus Fihlon disclaims all responsibility for any loss or damage which any person may suffer from reliance on this information or any opinion, conclusion or recommendation in this presentation whether the loss or damage is caused by any fault or negligence on the part of presenter or otherwise. 1
3. Session Material Slides, Code, Video http://fihlon.ch/jfs17 2
4. About Me Software Engineer CSS Insurance, Open Source Software Agile Coach CSS Insurance Lecturer TEKO Swiss Technical College Speaker Conferences, User Groups, Meetups Author Articles, Books www.fihlon.ch | github.com | hackergarten.net | jug.ch 3
5. What to expect History A brief retrospect in time. Motivation Why do we need a new API? Requirements Requirements for the new API. Boring slides Some theoretic stuff about the JSR-354. Source code Because we are hackers! 4
6. History float, double (since Java 1) java.math.BigDecimal (since Java 1.1) java.text.DecimalFormat (since Java 1.1) java.util.Currency (since Java 1.4) 5
7. Motivation Monetary values are a key feature for many applications java.util.Currency is a structure for ISO-4217 only No support for historic or virtual currencies No support for currency arithmetic or conversion No standard value type to represent a monetary amount java.text.DecimalFormat lacks flexibility 6
8. Requirements Easy addition and modification of currencies Currencies need a context and should be client-aware Standard API for money amounts, rounding, conversions Easy, flexible, complex, individual formatting and parsing Clearly defined extension points Follow the design principles of the Java platform Compatibility with Standard Edition and Micro Edition No external dependencies Interoperability with existing artefacts Support functional programming style 7
9. Three years of hard work JSR-354 started early 2012 JSR-354 early draft review in 2013 Reference implementation startet late 2013 Final release of JSR-354 early 2015 Final release of reference implementation early 2015 8
10. Highway of slides…
11. Currencies Monetary Get a currency by code or locale Additional API for complex queries Supports SPI to enhance functionality CurrencyUnit Currency code (string and number) Additional context information (e.g. type, capabilities) CurrencyQueryBuilder Builder for complex queries for accessing currency units 9
12. Monetary Amounts Monetary Get a monetary amount by currency and value Optionally specify an explicit factory Or query for a suitable factory Supports SPI to enhance functionality MonetaryAmount Numeric value and currency Arithmetic operations to do calculations Multiple implementations Interoperability rules Additional context information (e.g. capabilities) MonetaryAmountFactoryQueryBuilder Builder for complex queries for accessing monetary amount factories 10
13. Rounding Monetary Get a rounding operator Optionally specify a locale Or query for a suitable rounding operator Supports SPI to enhance functionality MonetaryRounding Extends MonetaryOperator Multiple implementations Additional context information RoundingQueryBuilder Builder for complex queries for accessing rounding operators 11
14. Conversion with currency conversion MonetaryConversions Get a currency conversion by currency code or unit Or query for a suitable currency conversion Supports SPI to enhance functionality CurrencyConversion Multiple implementations Source and target currency Conversion factor Additional context information Unidirectional ConversionQueryBuilder Builder for complex queries for accessing currency conversions 12
15. Conversion with exchange rate provider MonetaryConversions Get an exchange rate provider Or query for a suitable currency conversion Supports SPI to enhance functionality ExchangeRateProvider → ExchangeRate Multiple implementations Source and target currency Conversion factor Additional context information Unidirectional ConversionQueryBuilder Builder for complex queries for accessing exchange rate providers 13
16. Formatting and parsing MonetaryFormats Get a monetary amount format Optionally specify a locale Or query for a suitable monetary amount format Supports SPI to enhance functionality MonetaryAmountFormat Multiple implementations Additional context information Format monetary amounts Parse monetary amounts AmountFormatQueryBuilder Builder for complex queries for accessing monetary amount formats 14
17. Live Coding
18. Wrap-up
19. Interfaces CurrencyConversion CurrencySupplier CurrencyUnit ExchangeRate ExchangeRateProvider ExchangeRateProviderSupplier MonetaryAmount MonetaryAmountFormat MonetaryOperator MonetaryQuery MonetaryRounding NumberSupplier 15
20. Service Provider Interfaces CurrencyProviderSpi MonetaryAmountFactoryProviderSpi MonetaryAmountFormatProviderSpi MonetaryAmountsSingletonQuerySpi MonetaryAmountsSingletonSpi MonetaryConversionsSingletonSpi MonetaryCurrenciesSingletonSpi MonetaryFormatsSingletonSpi MonetaryRoundingsSingletonSpi RoundingProviderSpi 16
21. Validation Money Validation by Zalando Validate monetary amounts Uses existing, standardized constraints Offers additional, more expressive custom constraints Can be use with any Bean Validation implementation 1 @Min 2 @Max 3 @DecimalMin 4 @DecimalMax 5 @Positive 6 @PositiveOrZero 7 @Negative 8 @NegativeOrZero 9 @Zero 17
22. Compatibility Supports Java Micro Edition Java Standard Edition Java Enterprise Edition Compatible with Java 8+ Backport available for Java 7 18
23. Maven pom.xml 1 <dependency> 2 <groupId>javax.money</groupId> 3 <artifactId>money-api</artifactId> 4 <version>1.0.1</version> 5 </dependency> 6 <dependency> 7 <groupId>org.javamoney</groupId> 8 <artifactId>moneta</artifactId> 9 <version>1.1</version> 10 </dependency> 19
24. Gradle build.gradle 1 compile( 2 'javax.money:money-api:1.0.1', 3 'org.javamoney:moneta:1.1' 4 ) 20
25. Links Java Money Umbrella Site http://javamoney.org/ JSR-354 Specification http://javamoney.github.io/api.html JSR-354 Reference Implementation http://javamoney.github.io/ri.html JSR-354 Technical Compatibility Kit http://javamoney.github.io/tck.html Java Money Financial Library http://javamoney.github.io/lib.html Money Validation https://github.com/zalando/money-validation 21
26. The End Thank You! Questions? http://fihlon.ch/jfs17 22