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
   

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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.
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3. Session Material
   Slides, Code, Video
   http://fihlon.ch/jfs17
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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
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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!
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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)
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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
   

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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
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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
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10. Highway of slides…
    

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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
    

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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
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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
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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
    

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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
    

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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
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17. Live Coding
    

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18. Wrap-up
    

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19. Interfaces
    CurrencyConversion
    CurrencySupplier
    CurrencyUnit
    ExchangeRate
    ExchangeRateProvider
    ExchangeRateProviderSupplier
    MonetaryAmount
    MonetaryAmountFormat
    MonetaryOperator
    MonetaryQuery
    MonetaryRounding
    NumberSupplier
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20. Service Provider Interfaces
    CurrencyProviderSpi
    MonetaryAmountFactoryProviderSpi
    MonetaryAmountFormatProviderSpi
    MonetaryAmountsSingletonQuerySpi
    MonetaryAmountsSingletonSpi
    MonetaryConversionsSingletonSpi
    MonetaryCurrenciesSingletonSpi
    MonetaryFormatsSingletonSpi
    MonetaryRoundingsSingletonSpi
    RoundingProviderSpi
    16
    

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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
    

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22. Compatibility
    Supports
    Java Micro Edition
    Java Standard Edition
    Java Enterprise Edition
    Compatible with Java 8+
    Backport available for Java 7
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23. Maven
    pom.xml
    1
    2 javax.money
    3 money-api
    4 1.0.1
    5
    6
    7 org.javamoney
    8 moneta
    9 1.1
    10
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24. Gradle
    build.gradle
    1 compile(
    2 'javax.money:money-api:1.0.1',
    3 'org.javamoney:moneta:1.1'
    4 )
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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
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26. The End
    Thank You! Questions?
    http://fihlon.ch/jfs17
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