Groovy aims to simplify the life of Java developers by providing a more concise and readable syntax while maintaining compatibility with Java. Key features of Groovy include optional typing, semicolons and parentheses, and built-in support for lists, maps, regular expressions, and closures. Groovy code is very similar to Java code but removes some of the verbosity of Java for improved readability and productivity.

1. What makes
Groovy groovy?
Guillaume Laforge
@glaforge
© 2013 Guillaume Laforge. All rights reserved. Do not distribute without permission.

2. Guillaume
Laforge
Groovy project lead
at
.
@glaforge
http://glaforge.appspot.com

3. Les Cast
Codeurs

5. 1
t
r
a
P
The Groovy
vision

7. Simplify the life of
(Java) developers

16. Great for
scripting

17. Great for
scripting
Fit for DomainSpecific Languages

18. Great for
scripting
Fit for DomainSpecific Languages
Most seamless integration &
interoperability wih java!

20. It’s so easy
to learn!

21. Groovy as a
Java superset
It’s so easy
to learn!

23. class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}

25. As safe and fast as Java with
static type checking & compilation

26. As safe and fast as Java with
static type checking & compilation

28. new!MarkupBuilder().html!{
!!!!head!{
!!!!!!!!title!"The!Script!Bowl"
!!!!}
!!!!body!{
!!!!!!!!div(class:!"banner")!{
!!!!!!!!!!!!p!"Groovy!rocks!"
!!!!!!!!}
!!!!}
}

30. move!forward!at!3.km/h
Expressive,
Concise,
Readable

33. Speaking of conciseness...
A full Spring app in the span of a tweet!
@RestController
class!App!{
!!!!@RequestMapping("/")
!!!!String!home()!{!"Hello!World!"!}
}

34. • SmartThings
• Carriots
Services
• European Patent
Office
• Amadeus
IoT
Financial
• Crédit Suisse
• JPMorgan
• Fanny Mae
• Mutual of Omaha
• Hypoport
20
• Energy Transfer
• National Cancer Inst.
• IRSN
Internet
• Netflix
• LinkedIn
• Google
Technology
Who’s using Groovy?

35. 2
t
r
a
P
Cool Groovy
gems

37. Most Java code is also
valid Groovy code!

38. Most Java code is also
valid Groovy code!
Any Java developer is a
Groovy developer!

40. Flat learning
curve

41. Flat learning
curve
Easy to learn

42. Scripts versus Classes
public!class!Main!{
!!!!public!static!void!main(String[]!args)!{
!!!!!!!!System.out.println("Hello");
!!!!}
}
vs
24

43. Scripts versus Classes
public!class!Main!{
!!!!public!static!void!main(String[]!args)!{
!!!!!!!!System.out.println("Hello");
!!!!}
}
vs
println!"Hello"
24

44. Optional

45. Semicolons
Optional

46. Semicolons
Parentheses
Optional

47. Semicolons
Parentheses
Optional
return keyword

48. Semicolons
Parentheses
Optional
return keyword
public keyword

49. Semicolons
Parentheses
Optional
Typing!
return keyword
public keyword

50. Optional...
public!class!Greeter!{
!!!!private!String!owner;
!!!!public!String!getOwner()!{
!!!!!!!!return!owner;
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner;
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner;
!!!!}
}
Greeter!greeter!=!new!Greeter();
greeter.setOwner("Guillaume");
System.out.println(greeter.greet("Marion"));
26

51. Optional...
Semicolons
public!class!Greeter!{
!!!!private!String!owner;
!!!!public!String!getOwner()!{
!!!!!!!!return!owner;
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner;
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner;
!!!!}
}
Greeter!greeter!=!new!Greeter();
greeter.setOwner("Guillaume");
System.out.println(greeter.greet("Marion"));
26

52. Optional...
public!class!Greeter!{
!!!!private!String!owner
!!!!public!String!getOwner()!{
!!!!!!!!return!owner
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner("Guillaume")
System.out.println(greeter.greet("Marion"))
27

53. Optional...
public!class!Greeter!{
!!!!private!String!owner
!!!!public!String!getOwner()!{
!!!!!!!!return!owner
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner("Guillaume")
System.out.println(greeter.greet("Marion"))
28

54. Optional...
public!class!Greeter!{
!!!!private!String!owner
!!!!public!String!getOwner()!{
!!!!!!!!return!owner
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Parentheses
Greeter!greeter!=!new!Greeter()
greeter.setOwner("Guillaume")
System.out.println(greeter.greet("Marion"))
28

55. Optional...
public!class!Greeter!{
!!!!private!String!owner
!!!!public!String!getOwner()!{
!!!!!!!!return!owner
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
29

56. Optional...
public!class!Greeter!{
!!!!private!String!owner
!!!!public!String!getOwner()!{
!!!!!!!!return!owner
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
return keyword
!!!!public*String!greet(String!name)!{
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
29

57. Optional...
public!class!Greeter!{
!!!!private!String!owner
!!!!public!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
30

58. Optional...
public!class!Greeter!{
!!!!private!String!owner
!!!!public!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
public keyword
!!!!public!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!public*String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
30

59. Optional...
******!class!Greeter!{
!!!!private!String!owner
!!!!******!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!******!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Greeter!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
31

60. Optional...
******!class!Greeter!{
!!!!private!String!owner
!!!!******!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!******!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
optional typing
Greeter!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
31

61. Optional...
******!class!Greeter!{
!!!!private!String!owner
!!!!******!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!******!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
def!!!!!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
32

62. Optional...
******!class!Greeter!{
!!!!private!String!owner
!!!!******!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!******!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
handy println shortcut
def!!!!!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
System.out.println!greeter.greet("Marion")
32

63. Optional...
******!class!Greeter!{
!!!!private!String!owner
!!!!******!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!******!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
def!!!!!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
!!!!!!!!!!!println!greeter.greet("Marion")
33

64. Optional...
verbose Java properties!
******!class!Greeter!{
!!!!private!String!owner
!!!!******!String!getOwner()!{
!!!!!!!!******!owner
!!!!}
!!!!******!void!setOwner(String!owner)!{
!!!!!!!!this.owner!=!owner
!!!!}
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
def!!!!!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
!!!!!!!!!!!println!greeter.greet("Marion")
33

65. Optional...
******!class!Greeter!{
!!!!*******!String!owner
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
def!!!!!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
!!!!!!!!!!!println!greeter.greet("Marion")
34

66. Optional...
******!class!Greeter!{
!!!!*******!String!owner
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
Property notation
def!!!!!greeter!=!new!Greeter()
greeter.setOwner!"Guillaume"
!!!!!!!!!!!println!greeter.greet("Marion")
34

67. Optional...
******!class!Greeter!{
!!!!*******!String!owner
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
def!!!!!greeter!=!new!Greeter()
greeter.owner!!!!"Guillaume"
!!!!!!!!!!!println!greeter.greet("Marion")
35

68. Optional...
******!class!Greeter!{
!!!!*******!String!owner
Named argument
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
constructor
!!!!}
}
def!!!!!greeter!=!new!Greeter()
greeter.owner!!!!"Guillaume"
!!!!!!!!!!!println!greeter.greet("Marion")
35

69. Optional...
******!class!Greeter!{
!!!!*******!String!owner
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
def!!!!!greeter!=!new!Greeter(owner:!"Guillaume")
!!!!!!!!!!!println!greeter.greet("Marion")
36

70. Optional...
******!class!Greeter!{
!!!!*******!String!owner
Interpolated strings!
(aka GStrings)
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!"!+!name!+!",!I!am!"!+!owner
!!!!}
}
def!!!!!greeter!=!new!Greeter(owner:!"Guillaume")
!!!!!!!!!!!println!greeter.greet("Marion")
36

71. Optional...
******!class!Greeter!{
!!!!*******!String!owner
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!${name},!I!am!${owner}"
!!!!}
}
def!!!!!greeter!=!new!Greeter(owner:!"Guillaume")
!!!!!!!!!!!println!greeter.greet("Marion")
37

72. Optional...
******!class!Greeter!{
!!!!*******!String!owner
Let’s reformat that
mess of whitespace!
!!!!*******String!greet(String!name)!{
!!!!!!!!******!"Hello!${name},!I!am!${owner}"
!!!!}
}
def!!!!!greeter!=!new!Greeter(owner:!"Guillaume")
!!!!!!!!!!!println!greeter.greet("Marion")
37

73. Optional...
class!Greeter!{
***!String!owner
****String!greet(String!name)!{
******!"Hello!${name},!I!am!${owner}"
!!!!}
}
def!greeter!=!new!Greeter(owner:!"Guillaume")
println!greeter.greet("Marion")
38

74. Optional...
public!class!Greeter!{
!!!!private!String!owner;
!!!!public!String!getOwner()!{
class!Greeter!{
!!!!!!!!return!owner;
***!String!owner
!!!!}
****String!greet(String!name)!{
!!!!public!void!setOwner(String!owner)!{
******!"Hello!${name},!I!am!${owner}"
!!!!!!!!this.owner!=!owner;
!!!!}
!!!!}}
!!!!public*String!greet(String!name)!{
def!greeter!=!new!Greeter(owner:!"Guillaume")
!!!!!!!!return!"Hello!"!+!name!+!",!I!am!"!+!owner;
!!!!}println!greeter.greet("Marion")
}
Greeter!greeter!=!new!Greeter();
greeter.setOwner("Guillaume");
System.out.println(greeter.greet("Marion"));
38

75. Optional...
class!Greeter!{
***!String!owner
****String!greet(String!name)!{
******!"Hello!${name},!I!am!${owner}"
!!!!}
}
def!greeter!=!new!Greeter(owner:!"Guillaume")
println!greeter.greet("Marion")
38

76. Native syntax constructs
• Closures
• Lists
• Maps
• Regular expressions
• Ranges
39

77. Closures
• Functions as first-class citizen of the language
40

78. Lists
def!list!=!['a',!'b',!'c']
list!<<!'d'
assert!list.contains('d')
assert!list.findAll!{!it.startsWith!'a'!}.size()!==!1
assert!list.collect!{!it.toUpperCase()!}!==!['A',!'B',!'C',!'D']
assert!list.inject('')!{!a,!b!c>!a!+!b!}!==!'abcd'
41

79. Lists
List definition
def!list!=!['a',!'b',!'c']
list!<<!'d'
assert!list.contains('d')
assert!list.findAll!{!it.startsWith!'a'!}.size()!==!1
assert!list.collect!{!it.toUpperCase()!}!==!['A',!'B',!'C',!'D']
assert!list.inject('')!{!a,!b!c>!a!+!b!}!==!'abcd'
41

80. Lists
List definition
def!list!=!['a',!'b',!'c']
Append an element
(operator overloading)
list!<<!'d'
assert!list.contains('d')
assert!list.findAll!{!it.startsWith!'a'!}.size()!==!1
assert!list.collect!{!it.toUpperCase()!}!==!['A',!'B',!'C',!'D']
assert!list.inject('')!{!a,!b!c>!a!+!b!}!==!'abcd'
41

81. Lists
List definition
def!list!=!['a',!'b',!'c']
Append an element
(operator overloading)
list!<<!'d'
assert!list.contains('d')
assert!list.findAll!{!it.startsWith!'a'!}.size()!==!1
assert!list.collect!{!it.toUpperCase()!}!==!['A',!'B',!'C',!'D']
assert!list.inject('')!{!a,!b!c>!a!+!b!}!==!'abcd'
Functional-style
map / filter / reduce
with closures
41

82. Maps
def!map!=![name:!'Guillaume',!age:!36]
map.daughters!=!['Marion',!'Erine']
assert!map['daughters'].contains('Marion')
42

83. Maps
Map definition
def!map!=![name:!'Guillaume',!age:!36]
map.daughters!=!['Marion',!'Erine']
assert!map['daughters'].contains('Marion')
42

84. Maps
Map definition
def!map!=![name:!'Guillaume',!age:!36]
map.daughters!=!['Marion',!'Erine']
assert!map['daughters'].contains('Marion')
Indexed access
42

85. Maps
Map definition
def!map!=![name:!'Guillaume',!age:!36]
map.daughters!=!['Marion',!'Erine']
assert!map['daughters'].contains('Marion')
Property
notation access
42
Indexed access

86. Regular expressions
def!pattern!=!~/.*foo.*/
assert!"Alibaba"!==~!/.*(ba){2}/
def!matcher!=!"Superman"!=~!/([AcZ][acz]+)man/
assert!matcher[0][0]!==!'Superman'
assert!matcher[0][1]!==!'Super'
'75001!Paris'.find(/(d{5})s(w)+/)!{!match,!cp,!town!c>
!!!!println!"The!Zip!code!of!${town}!is!${cp}"
}
43

87. Regular expressions
Pattern
def!pattern!=!~/.*foo.*/
assert!"Alibaba"!==~!/.*(ba){2}/
def!matcher!=!"Superman"!=~!/([AcZ][acz]+)man/
assert!matcher[0][0]!==!'Superman'
assert!matcher[0][1]!==!'Super'
'75001!Paris'.find(/(d{5})s(w)+/)!{!match,!cp,!town!c>
!!!!println!"The!Zip!code!of!${town}!is!${cp}"
}
43

88. Regular expressions
Pattern
Match
def!pattern!=!~/.*foo.*/
assert!"Alibaba"!==~!/.*(ba){2}/
def!matcher!=!"Superman"!=~!/([AcZ][acz]+)man/
assert!matcher[0][0]!==!'Superman'
assert!matcher[0][1]!==!'Super'
'75001!Paris'.find(/(d{5})s(w)+/)!{!match,!cp,!town!c>
!!!!println!"The!Zip!code!of!${town}!is!${cp}"
}
43

89. Regular expressions
Pattern
Match
def!pattern!=!~/.*foo.*/
assert!"Alibaba"!==~!/.*(ba){2}/
Find
def!matcher!=!"Superman"!=~!/([AcZ][acz]+)man/
assert!matcher[0][0]!==!'Superman'
assert!matcher[0][1]!==!'Super'
'75001!Paris'.find(/(d{5})s(w)+/)!{!match,!cp,!town!c>
!!!!println!"The!Zip!code!of!${town}!is!${cp}"
}
43

90. Regular expressions
Pattern
Match
def!pattern!=!~/.*foo.*/
assert!"Alibaba"!==~!/.*(ba){2}/
Find
def!matcher!=!"Superman"!=~!/([AcZ][acz]+)man/
assert!matcher[0][0]!==!'Superman'
assert!matcher[0][1]!==!'Super'
'75001!Paris'.find(/(d{5})s(w)+/)!{!match,!cp,!town!c>
!!!!println!"The!Zip!code!of!${town}!is!${cp}"
}
Nice way to decompose the matched regions
43

91. Ranges
def!range!=!'a'..'z'
assert!range.contains('m')
assert!range.contains('z')
def!exclusive!=!1..<10
assert!!exclusive.contains(10)
def!reverse!=!10..0
assert!reverse[0]!==!10
assert!reverse[c1]!==!0
44

92. Ranges
Range
def!range!=!'a'..'z'
assert!range.contains('m')
assert!range.contains('z')
def!exclusive!=!1..<10
assert!!exclusive.contains(10)
def!reverse!=!10..0
assert!reverse[0]!==!10
assert!reverse[c1]!==!0
44

93. Ranges
Range
def!range!=!'a'..'z'
assert!range.contains('m')
assert!range.contains('z')
def!exclusive!=!1..<10
Excluded upper bound
assert!!exclusive.contains(10)
def!reverse!=!10..0
assert!reverse[0]!==!10
assert!reverse[c1]!==!0
44

94. Ranges
Range
def!range!=!'a'..'z'
assert!range.contains('m')
assert!range.contains('z')
def!exclusive!=!1..<10
Excluded upper bound
assert!!exclusive.contains(10)
def!reverse!=!10..0
assert!reverse[0]!==!10
assert!reverse[c1]!==!0
44
Reverse range

95. Ranges
Range
def!range!=!'a'..'z'
assert!range.contains('m')
assert!range.contains('z')
def!exclusive!=!1..<10
Excluded upper bound
assert!!exclusive.contains(10)
def!reverse!=!10..0
assert!reverse[0]!==!10
assert!reverse[c1]!==!0
44
Reverse range
Negative index count
from the end

96. Strings, GStrings, multiline strings
def!name!=!'Groovy'
def!tmpl!=!"""
!!!!Dear!Mr!${name},
!!!!You're!the!winner!of!the!lottery!
!!!!Yours!sincerly,
!!!!Dave
"""
assert!tmpl.toString().contains('Groovy')
45

97. Strings, GStrings, multiline strings
Plain java.lang.String
def!name!=!'Groovy'
def!tmpl!=!"""
!!!!Dear!Mr!${name},
!!!!You're!the!winner!of!the!lottery!
!!!!Yours!sincerly,
!!!!Dave
"""
assert!tmpl.toString().contains('Groovy')
45

98. Strings, GStrings, multiline strings
Plain java.lang.String
def!name!=!'Groovy'
Multiline string with
def!tmpl!=!"""
expression interpolation
!!!!Dear!Mr!${name},
!!!!You're!the!winner!of!the!lottery!
!!!!Yours!sincerly,
!!!!Dave
"""
assert!tmpl.toString().contains('Groovy')
45

99. Surprising numbers...
System.out.println(!2.0!c!1.1!);
46

100. Surprising numbers...
System.out.println(!2.0!c!1.1!);
0.8999999999999999
46

101. Surprising numbers...
System.out.println(!2.0!c!1.1!);
0.8999999999999999
46

102. Surprising numbers...
System.out.println(!3!/!2!);
47

103. Surprising numbers...
System.out.println(!3!/!2!);
1
47

104. Surprising numbers...
System.out.println(!3!/!2!);
1
47

105. BigDecimal by default!
assert!2.0!c!1.1!==!0.9
assert!3!/!2!==!1.5
48

106. BigDecimal by default!
assert!2.0!c!1.1!==!0.9
assert!3!/!2!==!1.5
One of the reasons why microbenchmarks sometimes showed
Groovy to be slow...
48

107. BigDecimal by default!
assert!2.0!c!1.1!==!0.9
assert!3!/!2!==!1.5
One of the reasons why microbenchmarks sometimes showed
Groovy to be slow...
48
But you can use doubles & floats
for performance, with ‘d’ or ‘f ’
suffixes or with explicit type

109. Powerful
switch / case
on steroids

110. Powerful
switch / case
on steroids
switch(obj)!{
!!!!case!123:!!!!!!!!!!!!!!!!!!"number!123";!!!!!!!!break
!!!!case!"abc":!!!!!!!!!!!!!!!!"string!abc";!!!!!!!!break
!!!!case!String:!!!!!!!!!!!!!!!"is!a!string";!!!!!!!break
!!!!case![1,!2,!3]:!!!!!!!!!!!!"contained!in!list";!break
!!!!case!~/.*o+.*/:!!!!!!!!!!!!"match!the!regex";!!!break
!!!!case!{!it.isUpperCase()!}:!"closure!criteria";!!break
****default:!"unknown"
}

111. Named arguments
move!obj,!x:!3,!y:!4
50

112. Named arguments
move!obj,!x:!3,!y:!4
Normal argument
50

113. Named arguments
move!obj,!x:!3,!y:!4
Normal argument
50
Named argument

114. Named arguments
move!obj,!x:!3,!y:!4
Normal argument
Calls:
move(Map m, Object)
50
Named argument

115. Command chains
• Ability to chain method calls
without parentheses and dots
51

116. Command chains
• Ability to chain method calls
without parentheses and dots
move!forward!at!3.km/h
51

117. Command chains
• Ability to chain method calls
without parentheses and dots
move!forward!at!3.km/h
Actually equivalent to:
move(forward).at(3.getKm().div(h))
51

118. Named arguments and command chains
check!that:!vodka!tastes!good
52

119. Named arguments and command chains
check!that:!vodka!tastes!good
Will call:
check(that: vodka).tastes(good)
52

120. Multiple assignment and destructuring
def!(a,!b)!=!['A',!'B']
(a,!b)!=![b,!a]
def!(int!i,!int!j)!=![1,!2]
def!geocode(String!place)!{
!!!!return![45.4,!2.3]
}
def!(la,!lo)!=!geocode("Paris")
assert!la!==!45.4!&&!lo!==!2.3
53

121. Multiple assignment and destructuring
def!(a,!b)!=!['A',!'B']
(a,!b)!=![b,!a]
Classic « swap »
def!(int!i,!int!j)!=![1,!2]
def!geocode(String!place)!{
!!!!return![45.4,!2.3]
}
def!(la,!lo)!=!geocode("Paris")
assert!la!==!45.4!&&!lo!==!2.3
53

122. Multiple assignment and destructuring
def!(a,!b)!=!['A',!'B']
With types
(a,!b)!=![b,!a]
Classic « swap »
def!(int!i,!int!j)!=![1,!2]
def!geocode(String!place)!{
!!!!return![45.4,!2.3]
}
def!(la,!lo)!=!geocode("Paris")
assert!la!==!45.4!&&!lo!==!2.3
53

123. Multiple assignment and destructuring
def!(a,!b)!=!['A',!'B']
With types
(a,!b)!=![b,!a]
Classic « swap »
def!(int!i,!int!j)!=![1,!2]
Method
returning a list
def!geocode(String!place)!{
!!!!return![45.4,!2.3]
}
def!(la,!lo)!=!geocode("Paris")
assert!la!==!45.4!&&!lo!==!2.3
53

124. Multiple assignment and destructuring
def!(a,!b)!=!['A',!'B']
With types
(a,!b)!=![b,!a]
Classic « swap »
def!(int!i,!int!j)!=![1,!2]
Method
returning a list
def!geocode(String!place)!{
!!!!return![45.4,!2.3]
}
Destructuring
def!(la,!lo)!=!geocode("Paris")
assert!la!==!45.4!&&!lo!==!2.3
53

125. Multiple assignment and destructuring
class!Point!{
!!!!double!x,!y
!!!!double!getAt(int!idx)!{
!!!!!!!!if!(idx!==!0)!x
!!!!!!!!else!if!(idx!==!1)!y
!!!!!!!!else!throw!new!Exception("Wrong!index")
!!!!}
}
def!(x,!y)!=!new!Point(x:!48.3,!y:!3.5)
assert!x!==!48.3!&&!y!==!3.5
54

126. Multiple assignment and destructuring
class!Point!{
!!!!double!x,!y
Method signature
convention: getAt(int)
!!!!double!getAt(int!idx)!{
!!!!!!!!if!(idx!==!0)!x
!!!!!!!!else!if!(idx!==!1)!y
!!!!!!!!else!throw!new!Exception("Wrong!index")
!!!!}
}
def!(x,!y)!=!new!Point(x:!48.3,!y:!3.5)
assert!x!==!48.3!&&!y!==!3.5
54

127. Multiple assignment and destructuring
class!Point!{
!!!!double!x,!y
Method signature
convention: getAt(int)
!!!!double!getAt(int!idx)!{
!!!!!!!!if!(idx!==!0)!x
!!!!!!!!else!if!(idx!==!1)!y
!!!!!!!!else!throw!new!Exception("Wrong!index")
!!!!}
}
Transparent destructuring
def!(x,!y)!=!new!Point(x:!48.3,!y:!3.5)
assert!x!==!48.3!&&!y!==!3.5
54

128. Builders and GPath expressions
import!groovy.xml.*
new!MarkupBuilder().html!{
!!!!head!{
!!!!!!!!title!"The!Script!Bowl"
!!!!}
!!!!body!{
!!!!!!!!div(class:!"banner")!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
!!!!}
}
55

129. Builders and GPath expressions
import!groovy.xml.*
Hierarchical data
representation
new!MarkupBuilder().html!{
!!!!head!{
!!!!!!!!title!"The!Script!Bowl"
!!!!}
!!!!body!{
!!!!!!!!div(class:!"banner")!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
!!!!}
}
55

130. Builders and GPath expressions
import!groovy.xml.*
Hierarchical data
representation
new!MarkupBuilder().html!{
!!!!head!{
!!!!!!!!title!"The!Script!Bowl"
!!!!}
!!!!body!{
!!!!!!!!div(class:!"banner")!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
Closure blocks delimiting
!!!!}
the structure
}
55

131. Builders and GPath expressions
import!groovy.xml.*
Hierarchical data
representation
new!MarkupBuilder().html!{
!!!!head!{
!!!!!!!!title!"The!Script!Bowl"
!!!!}
Attributes
!!!!body!{
!!!!!!!!div(class:!"banner")!{
!!!!!!!!!!!!p!"Groovy!won!"
!!!!!!!!}
Closure blocks delimiting
!!!!}
the structure
}
55

132. Power asserts
def!(a,!b,!c)!=![20,!30,!40]
assert!a!*!(b!c!1)!/!10!==!3!*!c!/!2!+!1
56

133. Power asserts
def!(a,!b,!c)!=![20,!30,!40]
assert!a!*!(b!c!1)!/!10!==!3!*!c!/!2!+!1
Assertion!failed:!
assert!a!*!(b!c!1)!/!10!==!3!*!c!/!2!+!1
!!!!!!!|!|!!|!|!!!!|!!!!|!!!!|!|!|!!!|
!!!!!!!|!580|!29!!!58!!!false|!|!60!!61
!!!!!!!20!!!30!!!!!!!!!!!!!!!|!40
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!120
! at!script1.run(script1t.groovy:4)
56

134. Null handling
• Groovy provides a more descriptive
NullPointerException than Java
• Safe navigation with ?.
57

136. The Truth,
the Groovy Truth!

137. The Truth,
the Groovy Truth!
And what if I could
customize the truth?

138. ?:

139. ?:
The Elvis
operator!

140. Towards Elvis...
60

141. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
60

142. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
60

143. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
if*(x!&&!x.size())!x!else!y
60

144. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
if*(x!&&!x.size())!x!else!y
if*(x)!x!else!y
60

145. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
if*(x!&&!x.size())!x!else!y
if*(x)!x!else!y
x!?!x!:!y
60

146. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
if*(x!&&!x.size())!x!else!y
if*(x)!x!else!y
x!?!x!:!y
x!?:!y
60

147. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
if*(x!&&!x.size())!x!else!y
if*(x)!x!else!y
x!?!x!:!y
x!?:!y
Null, empty, zerosized... false,
otherwise true!
60

148. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
if*(x!&&!x.size())!x!else!y
if*(x)!x!else!y
x!?!x!:!y
x!?:!y
Good old ternary
operator
60
Null, empty, zerosized... false,
otherwise true!

149. Towards Elvis...
def!(x,!y)!=!['MacBook!Pro',!'unknown']
if*(x!!=!null!&&!x.size()!>!0)!x!else!y
if*(x!&&!x.size())!x!else!y
if*(x)!x!else!y
x!?!x!:!y
x!?:!y
Elvis!
60
Good old ternary
operator
Null, empty, zerosized... false,
otherwise true!

150. AST transformations
• Abstract Syntax Tree
– in memory representation of your program
before being compiled into bytecode
• AST transformation == process of transforming
the AST of a program before it’s compiled
• Macro-like compiler hook!
61

151. Lots of AST transformations...
• Code generation
– @ToString, @EqualsAndHashCode, @Canonical,
@TupleConstructor, @InheritConstructors,
@Category, @IndexedProperty, @Lazy, @Newify
• Class design
– @Delegate, @Immutable, @Memoized,
@Singleton, @Mixin
• Logging
– @Log, @Log4j, @Log4j2, @Slf4j
62

152. Lots of AST transformations...
• Safer scripting
– @ConditionalInterrupt, @ThreadInterrupt,
@TimedInterupt
• Compiler directives
– @Field, @PackageScope, @AnnotationCollector,
@DelegatesTo, @TypeChecked,
@CompileStatic, @CompileDynamic
• Swing patterns
– @Bindable, @ListenerList, @Vetoable
63

153. Lots of AST transformations...
• Dependencies handling
– @Grab, @GrabConfig, @GrabExclude,
@GrabResolver
• Test assistance
– @NotYetImplemented, @ASTTest
64

154. Immutability
• Implement immutability
by the book
– final class
– tuple-style constructor
– private final backing fields
– defensive copying of collections
– equals() and hashCode() methods
– toString() method
– ...
65

155. Immutability
• Implement immutability
by the book
– final class
Can be error-prone to
– tuple-style constructor
write immutable
– private final backing fields
classes oneself!
– defensive copying of collections
– equals() and hashCode() methods
– toString() method
– ...
65

156. Immutability
• A Person class with
public final class Person {
private final String name;
private final int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
– a String name
– an int age
public String getName() {
return name;
}
public int getAge() {
return age;
}
public int hashCode() {
return age + 31 * name.hashCode();
}
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (this == other) {
return true;
}
if (Person.class != other.getClass()) {
return false;
}
Person otherPerson = (Person)other;
if (!name.equals(otherPerson.getName()) {
return false;
}
if (age != otherPerson.getAge()) {
return false;
}
return true;
}
public String toString() {
return "Person(" + name + ", " + age + ")";
}
}
66

157. Immutability
• A Person class with
Damn
verbose
Java!
public final class Person {
private final String name;
private final int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
– a String name
– an int age
public String getName() {
return name;
}
public int getAge() {
return age;
}
public int hashCode() {
return age + 31 * name.hashCode();
}
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (this == other) {
return true;
}
if (Person.class != other.getClass()) {
return false;
}
Person otherPerson = (Person)other;
if (!name.equals(otherPerson.getName()) {
return false;
}
if (age != otherPerson.getAge()) {
return false;
}
return true;
}
public String toString() {
return "Person(" + name + ", " + age + ")";
}
}
66

158. Immutability
• A Person class with
Damn
verbose
Java!
public final class Person {
private final String name;
private final int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
– a String name
– an int age
public String getName() {
return name;
}
public int getAge() {
return age;
}
public int hashCode() {
return age + 31 * name.hashCode();
}
public boolean equals(Object other) {
if (other == null) {
return false;
}
if (this == other) {
return true;
}
if (Person.class != other.getClass()) {
return false;
}
Person otherPerson = (Person)other;
if (!name.equals(otherPerson.getName()) {
return false;
}
if (age != otherPerson.getAge()) {
return false;
}
return true;
}
Although it’s also a valid
Groovy program!
public String toString() {
return "Person(" + name + ", " + age + ")";
}
}
66

159. @Immutable
import!groovy.transform.*
@Immutable
class!Person!{
!!!!String!name
!!!!int!age
}
67

160. Memoization
• Cache the result of previous invocations
of closures or methods with the same set
of argument values
import!groovy.transform.*
@Memoized
long!fib(long!n)!{
!!!!if!(n!==!0)!0
!!!!else!if!(n!==!1)!1
!!!!else!fib(n!c!1)!+!fib(n!c!2)
}
println!fib(40)
68

161. Memoization
• Cache the result of previous invocations
of closures or methods with the same set
of argument values
import!groovy.transform.*
Best applied to
side-effect free
functions
@Memoized
long!fib(long!n)!{
!!!!if!(n!==!0)!0
!!!!else!if!(n!==!1)!1
!!!!else!fib(n!c!1)!+!fib(n!c!2)
}
println!fib(40)
68

163. Groovy allows you
to be lazy

164. Groovy allows you
to be lazy
The compiler will do
the job for you

165. Groovy allows you
to be lazy
More concise, more
readable code
The compiler will do
the job for you

166. Groovy allows you
to be lazy
More concise, more
readable code
The compiler will do
the job for you
Less stuff to maintain
and worry about

167. @TypeChecked and @CompileStatic
• Static type checking with @TypeChecked,
throws compilation errors on...
– typos in method and variable names
– incompatible return types
– wrong type assignments
• Supports fine-grained type inference
– « Least Upper Bound »
– « Flow typing »
70

168. @TypeChecked and @CompileStatic
• Static type checking with @TypeChecked,
throws compilation errors on...
– typos in method and variable names
– incompatible return types
You can even extend the
– wrong type assignments
static type checker!
• Supports fine-grained type inference
– « Least Upper Bound »
– « Flow typing »
70

169. @TypeChecked and @CompileStatic
• Static type checking with @TypeChecked,
throws compilation errors on...
– typos in method and variable names
– incompatible return types
You can even extend the
– wrong type assignments
static type checker!
• Supports fine-grained type inference
– « Least Upper Bound »
– « Flow typing »
70
Type check DSLs or
dynamic features!

170. @TypeChecked and @CompileStatic
• What is type checked can also be compiled
statically with @CompileStatic
– generate the same bytecode as javac
– same performance as Java
71

171. Pi (π)
Fibonacci
quadrature
Java
191 ms
97 ms
3.6 s
2.x
Static
compilation
197 ms
101 ms
4.3 s
1.8
72
Binary
trees
Primitive
optimizations
360 ms
111 ms
23.7 s
1.7
Static compilation performance
No prim.
optimizations
2590 ms 3220 ms
50.0 s

172. 3
t
r
a
P
Superb
community!

173. A blossoming
Ecosystem

178. M
V
G

180. GVM

181. GVM
GROOVY
ENVIRONMENT
MANAGER

182. GVM: Groovy enVironment Manager
• The new kid on the block
– http://gvmtool.net/ — @gvmtool
• Manage parallel versions
of the various ecosystem projects
• Supports...
– Groovy, Grails, Griffon, Gradle,Vert.x, Spring Boot
• On Linux, MacOS, Cygwin, Solaris, FreeBSD
81

184. I’m Spock...

185. I’m Spock...
...the Spock testing
framework

186. I’m Spock...
...the Spock testing
framework

187. Spock example
@Grab('org.spockframework:spockccore:0.7cgroovyc2.0')
import!spock.lang.*
class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

188. Spock example
@Grab a dependency
@Grab('org.spockframework:spockccore:0.7cgroovyc2.0')
import!spock.lang.*
class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83

189. Spock example
@Grab a dependency
@Grab('org.spockframework:spockccore:0.7cgroovyc2.0')
import!spock.lang.*
class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83
Meaningful test
method names

190. Spock example
@Grab a dependency
@Grab('org.spockframework:spockccore:0.7cgroovyc2.0')
import!spock.lang.*
Meaningful test
method names
class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
Clever use of labels
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83
for BDD style

191. Spock example
@Grab a dependency
@Grab('org.spockframework:spockccore:0.7cgroovyc2.0')
import!spock.lang.*
Meaningful test
method names
class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
Clever use of labels
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83
for BDD style
Expression to
be asserted

192. Spock example
@Grab a dependency
@Grab('org.spockframework:spockccore:0.7cgroovyc2.0')
import!spock.lang.*
Meaningful test
method names
class!MathSpec!extends!Specification!{
!!!!def!"maximum!of!two!numbers"()!{
******expect:
!!!!!!!!Math.max(a,!b)!==!c
Clever use of labels
******where:
!!!!!!!!a!|!b!||!c
!!!!!!!!1!|!3!||!3
!!!!!!!!7!|!4!||!4
!!!!!!!!0!|!0!||!0
!!!!}
}
83
for BDD style
Cute datadriven tests!
Expression to
be asserted

194. @GrabResolver("https://oss.jfrog.org/artifactory/repo")
@Grab("org.ratpackcframework:ratpackcgroovy:0.9.0cSNAPSHOT")
import!static!org.ratpackframework.groovy.RatpackScript.ratpack
import!static!org.ratpackframework.groovy.Template.groovyTemplate
ratpack!{
!!!!handlers!{
!!!!!!!!get!{
!!!!!!!!!!!!response.send!"Welcome!"
!!!!!!!!}
!!!!!!!!get("date")!{
!!!!!!!!!!!!render!groovyTemplate("date.html")
!!!!!!!!}
!!!!!!!!assets!"public"
!!!!}
}

195. @GrabResolver("https://oss.jfrog.org/artifactory/repo")
@Grab("org.ratpackcframework:ratpackcgroovy:0.9.0cSNAPSHOT")
import!static!org.ratpackframework.groovy.RatpackScript.ratpack
import!static!org.ratpackframework.groovy.Template.groovyTemplate
ratpack!{
!!!!handlers!{
!!!!!!!!get!{
!!!!!!!!!!!!response.send!"Welcome!"
!!!!!!!!}
Lightweight Netty-based
web app toolkit
!!!!!!!!get("date")!{
!!!!!!!!!!!!render!groovyTemplate("date.html")
!!!!!!!!}
!!!!!!!!assets!"public"
!!!!}
}

196. Geb
• Browser automation solution
• WebDriver + jQuery selectors + Groovy
• Handy for
– scripting, scraping, automation...
– functional / web / acceptance testing
• when integrated with JUnit, TestNG or Spock
85

197. Geb — Example
import!geb.Browser
Browser.drive!{
!!!!go!"http://myapp.com/login"
!!!!assert!$("h1").text()!==!"Please!Login"
!!!!$("form.login").with!{
!!!!!!!!username!=!"admin"
!!!!!!!!password!=!"password"
!!!!!!!!login().click()
!!!!}
!!!!assert!$("h1").text()!==!
!!!!!!!!"Admin!Section"
}
86

198. Geb — Example
Drive the browser
to this site
import!geb.Browser
Browser.drive!{
!!!!go!"http://myapp.com/login"
!!!!assert!$("h1").text()!==!"Please!Login"
!!!!$("form.login").with!{
!!!!!!!!username!=!"admin"
!!!!!!!!password!=!"password"
!!!!!!!!login().click()
!!!!}
!!!!assert!$("h1").text()!==!
!!!!!!!!"Admin!Section"
}
86

199. Geb — Example
Drive the browser
to this site
import!geb.Browser
Browser.drive!{
!!!!go!"http://myapp.com/login"
Check the content
of the title
!!!!assert!$("h1").text()!==!"Please!Login"
!!!!$("form.login").with!{
!!!!!!!!username!=!"admin"
!!!!!!!!password!=!"password"
!!!!!!!!login().click()
!!!!}
!!!!assert!$("h1").text()!==!
!!!!!!!!"Admin!Section"
}
86

200. Geb — Example
Drive the browser
to this site
import!geb.Browser
Browser.drive!{
!!!!go!"http://myapp.com/login"
Check the content
of the title
!!!!assert!$("h1").text()!==!"Please!Login"
!!!!$("form.login").with!{
!!!!!!!!username!=!"admin"
!!!!!!!!password!=!"password"
!!!!!!!!login().click()
!!!!}
!!!!assert!$("h1").text()!==!
!!!!!!!!"Admin!Section"
}
86
Find & fill in
the form

201. Geb — Example
Drive the browser
to this site
import!geb.Browser
Browser.drive!{
!!!!go!"http://myapp.com/login"
Check the content
of the title
!!!!assert!$("h1").text()!==!"Please!Login"
!!!!$("form.login").with!{
!!!!!!!!username!=!"admin"
!!!!!!!!password!=!"password"
!!!!!!!!login().click()
!!!!}
!!!!assert!$("h1").text()!==!
!!!!!!!!"Admin!Section"
}
86
Find & fill in
the form
Submit the
form

202. Geb — Example
Drive the browser
to this site
import!geb.Browser
Browser.drive!{
!!!!go!"http://myapp.com/login"
Check the content
of the title
!!!!assert!$("h1").text()!==!"Please!Login"
!!!!$("form.login").with!{
!!!!!!!!username!=!"admin"
!!!!!!!!password!=!"password"
!!!!!!!!login().click()
!!!!}
!!!!assert!$("h1").text()!==!
!!!!!!!!"Admin!Section"
}
Find & fill in
the form
Submit the
form
In the admin section, yeah!
86

203. Geb — With page objects and Spock
import!geb.spock.GebSpec
class!GoogleWikipediaSpec!extends!GebSpec!{
!!!!def!"first!result!for!wikipedia!search!should!be!wikipedia"()!{
********given:
!!!!!!!!to!GoogleHomePage
********expect:
!!!!!!!!at!GoogleHomePage
********when:
!!!!!!!!search.field.value("wikipedia")
********then:
!!!!!!!!waitFor!{!at!GoogleResultsPage!}
********and:
!!!!!!!!firstResultLink.text()!==!"Wikipedia"
********when:
!!!!!!!!firstResultLink.click()
********then:
!!!!!!!!waitFor!{!at!WikipediaPage!}
!!!!}
}
87

204. Geb — With page objects and Spock
import!geb.spock.GebSpec
class!GoogleWikipediaSpec!extends!GebSpec!{
With page objects
!!!!def!"first!result!for!wikipedia!search!should!be!wikipedia"()!{
********given:
!!!!!!!!to!GoogleHomePage
********expect:
!!!!!!!!at!GoogleHomePage
********when:
!!!!!!!!search.field.value("wikipedia")
********then:
!!!!!!!!waitFor!{!at!GoogleResultsPage!}
********and:
!!!!!!!!firstResultLink.text()!==!"Wikipedia"
********when:
!!!!!!!!firstResultLink.click()
********then:
!!!!!!!!waitFor!{!at!WikipediaPage!}
!!!!}
}
87

205. Geb — With page objects and Spock
import!geb.spock.GebSpec
class!GoogleWikipediaSpec!extends!GebSpec!{
With page objects
!!!!def!"first!result!for!wikipedia!search!should!be!wikipedia"()!{
********given:
!!!!!!!!to!GoogleHomePage
********expect:
!!!!!!!!at!GoogleHomePage
BDD style: given/when/then
********when:
!!!!!!!!search.field.value("wikipedia")
********then:
!!!!!!!!waitFor!{!at!GoogleResultsPage!}
********and:
!!!!!!!!firstResultLink.text()!==!"Wikipedia"
********when:
!!!!!!!!firstResultLink.click()
********then:
!!!!!!!!waitFor!{!at!WikipediaPage!}
!!!!}
}
87

206. Geb — With page objects and Spock
import!geb.spock.GebSpec
class!GoogleWikipediaSpec!extends!GebSpec!{
With page objects
!!!!def!"first!result!for!wikipedia!search!should!be!wikipedia"()!{
********given:
!!!!!!!!to!GoogleHomePage
********expect:
!!!!!!!!at!GoogleHomePage
********when:
!!!!!!!!search.field.value("wikipedia")
BDD style: given/when/then
Wait for slow loading pages
********then:
!!!!!!!!waitFor!{!at!GoogleResultsPage!}
********and:
!!!!!!!!firstResultLink.text()!==!"Wikipedia"
********when:
!!!!!!!!firstResultLink.click()
********then:
!!!!!!!!waitFor!{!at!WikipediaPage!}
!!!!}
}
87

207. 4
t
r
a
P
Summary

208. Java’s best friend
• Java derived syntax
– Flat learning curve
– Easy to learn
• But goes beyond Java
– Concise, expressive, readable
– Fit for Domain-Specific Languages
• Seamless & transparent Java integration
– Mix and match Groovy and Java classes (joint compil.)
– No language barrier to cross
89

209. Groovy’s nature
• Object oriented dynamic language...
• But...
– as type safe as you want it — static type checking
– as fast as you need it — static compilation
– as functional as you make it — closures...
90

210. Groovy use cases
• Scripting tasks, build automation
• Extension points for customizing/configuring apps
• Business languages & Domain-Specific Languages
• Full blown apps
– for desktop with Griffon
– for the web with Grails, Ratpack, Gaelyk
– for web reactive programming with reactor
91