- Groovy is a JVM language that compiles to Java bytecodes and interoperates seamlessly with Java. - It simplifies Java development with features like optional semicolons, optional parentheses, and native collections. - Groovy also includes closures, builders, metaprogramming capabilities, and tools like Spock for testing and Gradle for building.

1. Making Java Groovy
Simplify Your Java Development
With Groovy
JavaOne 2013

2. Contact Info
Ken Kousen
President, Kousen IT, Inc.
www.kousenit.com
ken.kousen@kousenit.com
@kenkousen
Making Java Groovy
http://manning.com/kousen

3. Groovy
JVM language

4. Groovy
JVM language
compiles to bytecodes

5. Groovy
JVM language
compiles to bytecodes
optional semicolons

6. Groovy
JVM language
compiles to bytecodes
optional semicolons
optional parentheses

7. Groovy
JVM language
compiles to bytecodes
optional semicolons
optional parentheses
everything is an object

8. Adding Groovy to Java

9. Adding Groovy to Java
Actually, Boromir, One Does

10. Adding Groovy to Java
Actually, Boromir, One Does
(and simply)

11. Adding Groovy to Java
Actually, Boromir, One Does
(and simply)
(and btw, Lord Stark, you might want
to stay out
of King’s Landing…)

12. Adding Groovy to Java
Demo: Execute compiled Groovy
with java command

13. Operator Overloading
All operators in Groovy invoke methods

14. Operator Overloading
All operators in Groovy invoke methods
a + b a.plus(b)
a – b a.minus(b)
a * b a.multiply(b)
a[b] a.getAt(b)
a[b] = c a.putAt(b,c)
a == b a.equals(b) or
a.compareTo(b)

15. Operator Overloading
All operators in Groovy invoke methods
http://groovy.codehaus.org/Operator+Overloading
a + b a.plus(b)
a – b a.minus(b)
a * b a.multiply(b)
a[b] a.getAt(b)
a[b] = c a.putAt(b,c)
a == b a.equals(b) or
a.compareTo(b)

17. POGOs
Actually, YES

18. POGOs
Actually, YES
Plain Old Groovy Objects

19. POGOs
Generated getters / setters

20. POGOs
Generated getters / setters
Map-based constructor

21. POGOs
Generated getters / setters
Map-based constructor
AST transformations
@ToString
@EqualsAndHashCode
@TupleConstructor
@Canonical

22. Adding Groovy to Java
Demo:
Account class in Groovy
NumberFormat from Java
Test in Java

24. Collections
Okay, make it so…

25. Collections
Okay, make it so…
Native collections

26. Collections
Okay, make it so…
Native collections
Ranges

27. Collections
Okay, make it so…
Native collections
Ranges
Lists and Sets

28. Collections
Okay, make it so…
Native collections
Ranges
Lists and Sets
Maps

29. Ranges
Implement Comparable
next()
previous()
Number, Date, String, …

30. Lists
[3, 1, 4, 1, 5, 9, …]
['this', 'is', 'a', 'list’]

31. Sets
[3, 1, 4, 1, 5, 9, …] as Set
Set strings

32. Maps
def map = [a:1, b:2, c:3]
map.d = 4
map['e'] = 5
map.put('f', 6)

33. Closures
{ … it … }
{ x, y -> x + y }

34. Closures
{ … it … }
{ x, y -> x + y }
anonymous functions as first-class objects

35. Closures
{ … it … }
{ x, y -> x + y }
anonymous functions as first-class objects
(oversimplified, but it’s a start…)

36. Closures
Methods on collections:
each
collect
findAll
inject

37. Functional Groovy
Closures  lambdas (if pure)
collect  map
findAll  filter
inject  reduce

39. Groovy JDK
Java classes enhanced by Groovy
through metaprogramming
Number
String
Date
Collection
URL
…

40. RESTful Web Service
Google v3 Geocoder
Convert addresses to latitude / longitude

41. Geocoder
Base URL
URLEncoder.encode(it, 'UTF-8').join(',’)

42. Geocoder
Base URL
URLEncoder.encode(it, 'UTF-8').join(',’)
params.collect { k,v -> "$k=$v"
}.join('&')

43. Geocoder
Base URL
URLEncoder.encode(it, 'UTF-8').join(',’)
params.collect { k,v -> "$k=$v"
}.join('&')
XmlSlurper.parse("$base$qs")

45. JSON
ICNDB  the Internet Chuck Norris Database
http://api.icndb.com/jokes/random?
limitTo=[nerdy]&
firstName=…&
lastName=…

46. ICNDB
JsonSlurper
Metaprogramming

47. Spock Testing

48. Spock
Specification + Mock

49. Spock
Specification + Mock
Includes JUnit runner

50. Spock
Specification + Mock
Includes JUnit runner
Data-driven tests

51. Spock
Specification + Mock
Includes JUnit runner
Data-driven tests
Database-driven tests

52. Gradle
Build tool

53. Gradle
Build tool
DSL for builds

54. Gradle
Build tool
DSL for builds
Build script in Groovy rather than XML

55. Gradle
Build tool
DSL for builds
Build script in Groovy rather than XML
Used by:
Hibernate, Spring, Android, …

57. Summary
Groovy compiles to bytecodes
Groovy JDK
Native collections
Closures
Builders
Metaprogramming