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hansamann on 04/17/07


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Switch groovyseries for if else else-if while


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Groovy Series: Groovy Control Structures

Published in: Groovy 

URL: http://hansamann.podspot.de/files/grails_podcast_episode_40.mp3

This snippet gives you some interesting examples about Groovy Control Structures. Listen to the audio to get the best learning experience. Simply right-click on the title above to download the mp3 file of this part of the series.

The Groovy Series is part of the Grails Podcast and can be subscribed to via: http://hansamann.podspot.de/rss. The series is produced by Dierk König and Sven Haiges, further information about the topic of this episode can be found in the book

Groovy in Action - http://groovy.canoo.com/gina


Plain TextExpand 
  1. //if / else if / else 
  2. def x = 1
  3. if (x) assert true
  4. else if (!x) assert false
  5. else assert false
  6.  
  7.  
  8. //conditional ?:
  9. def obj = new Object()
  10. def txt = obj ? 'true' : 'false'
  11. assert txt == 'true'
  12.  
  13. def myList = []
  14. assert 'empty' == (myList ? 'not empty' : 'empty')
  15.  
  16. //powerful switch statement, isCase() :-)
  17. def someValue = 5
  18. def feedback = ''
  19. switch (someValue) {
  20.     case 1..3 : feedback = 'quite ok'; break
  21.     case 3..6 : feedback = 'needs improvement'; break
  22.     default: feedback = 'unknown'
  23. }    
  24. assert (feedback == 'needs improvement')
  25.  
  26. //java.lang.Class contains an isCase() method, we can classify by class
  27. someValue = 5.5
  28. feedback = ''
  29. switch (someValue) {
  30. 	case Float: feedback = /It's a Float/; break
  31.  	case Integer: feedback = /It's an Integer/; break
  32. 	case BigDecimal: feedback = /It's a BigDecimal/; break
  33. 	default: feedback = 'You are using an unknown number type!'
  34. }
  35. assert (feedback == /It's a BigDecimal/)
  36.  
  37.  
  38. //switching on Lists
  39. someValue = 4
  40. feedback = ''
  41. switch (someValue) {
  42. 	case [1,2,3]: feedback = 'One, Two or Three' ; break
  43. 	case [4,5,6]: feedback = 'Four, Five or Six'; break;
  44. }
  45. assert (feedback == 'Four, Five or Six')
  46.  
  47. //matcher with switch
  48. someValue = 'Hello World'
  49. feedback = ''
  50. switch (someValue) {
  51. 	case ~/Guten Tag/: feedback = 'Guten Tag'; break;
  52. 	case ~/^Hello.*/: feedback = 'Starts with Hello'
  53. }
  54. assert (feedback == 'Starts with Hello')
  55.  
  56. //for
  57. //pretty standard java5 for loop in groovy
  58. def myList = ['groovy',' ', 'is', ' ', 'cool']
  59. def result = ''
  60. for (item in myList) {
  61. 	result += item
  62. }
  63. assert (result == 'groovy is cool')
  64.  
  65.  
  66. //using ranges in for loops
  67. result = new StringBuffer()
  68. for (character in 'a'..'f') {
  69. 	result << character
  70. }
  71. assert (result.toString() == 'abcdef')
  72.  
  73. //using for with a matcher
  74. def times = []
  75. def text = 'Get up at 8:00, have coffee at 8:15 and go to work around 11:00'
  76. def timeMatcher = text =~ /\d{1,2}:\d\d/
  77. for (match in timeMatcher) times << match
  78. assert (times.join(',') == '8:00,8:15,11:00')
  79.  
  80. //classic for loops will come with groovy 1.1 :-)

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