From Java to Groovy, the easy way

This short presentation introduces to the Groovy language, coming from Java.

Transcript

1. From Java to Groovy The easy way
2. Eyal LEZMY http://eyal.fr SLIDES http://bit.ly/JA2GR
3. What’s Groovy? Alternative language for the JVM Compiles bytecode Statically or at Runtime Can use Java libraries
4. From Java to Groovy 01 by Guillaume Laforge
5. public class HelloWorld { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } public String greet() { return "Hello " + name; } public static void main(String[] args) { HelloWorld helloWorld = new HelloWorld(); helloWorld.setName("Groovy"); System.out.println( helloWorld.greet() ); } } From JAVA
6. public class HelloWorld { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } public String greet() { return "Hello " + name; } public static void main(String[] args) { HelloWorld helloWorld = new HelloWorld(); helloWorld.setName("Groovy"); System.out.println( helloWorld.greet() ); } } To GROOVY
7. public class HelloWorld { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } public String greet() { return "Hello " + name; } public static void main(String[] args) { HelloWorld helloWorld = new HelloWorld(); helloWorld.setName("Groovy"); System.out.println( helloWorld.greet() ); } } To GROOVY
8. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello " + name } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
9. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello " + name } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
10. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello ${name}" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
11. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello ${name}" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY GString => double quotes (“ ”)
12. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
13. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
14. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY Private field
15. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY Getter & Setter Private field
16. class HelloWorld { private String name void setName(String name) { this.name = name } String getName() { return name } String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
17. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
18. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
19. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.setName("Groovy") System.out.println( helloWorld.greet() ) } } To GROOVY
20. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.name = "Groovy" System.out.println( helloWorld.greet() ) } } To GROOVY
21. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.name = "Groovy" System.out.println( helloWorld.greet() ) } } To GROOVY
22. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.name = "Groovy" System.out.println( helloWorld.greet() ) } } To GROOVY
23. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.name = "Groovy" println( helloWorld.greet() ) } } To GROOVY
24. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.name = "Groovy" println( helloWorld.greet() ) } } To GROOVY
25. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.name = "Groovy" println helloWorld.greet() } } To GROOVY
26. class HelloWorld { String name String greet() { return "Hello $name" } static void main(String[] args) { HelloWorld helloWorld = new HelloWorld() helloWorld.name = "Groovy" println helloWorld.greet() } } To GROOVY
27. class HelloWorld { def name def greet() { return "Hello $name" } static main(args) { def helloWorld = new HelloWorld() helloWorld.name = "Groovy" println helloWorld.greet() } } To GROOVY
28. class HelloWorld { def name def greet() { return "Hello $name" } static main(args) { def helloWorld = new HelloWorld() helloWorld.name = "Groovy" println helloWorld.greet() } } To GROOVY
29. class HelloWorld { def name def greet() { return "Hello $name" } static main(args) { def helloWorld = new HelloWorld() helloWorld.name = "Groovy" println helloWorld.greet() } } To GROOVY
30. class HelloWorld { def name def greet() { return "Hello $name" } } def helloWorld = new HelloWorld() helloWorld.name = "Groovy" println helloWorld.greet() To GROOVY
31. public class HelloWorld { private String name; public void setName(String name) { this.name = name; } public String getName() { return name; } public String greet() { return "Hello " + name; } public static void main(String[] args) { HelloWorld helloWorld = new HelloWorld(); helloWorld.setName("Groovy"); System.out.println( helloWorld.greet() ); } } From JAVA
32. Where the Magic happens... 02
33. Methods Default value parameters Named parameters No return statement Return multiple variables Groovy Methods
34. def createGenyboy(gender = “male”) { … if(gender == “male”) name = “Genyboy” … [name, color, size] } def(String name, Color color, int size) = createGenyboy(gender:“female”) Groovy Methods
35. static def cmd(def command, Closure c){ Process p = command.execute() p.text.eachLine {line, count -> c(line, count) } p.exitValue() } a = “hello” cmd(“gmtool admin list”) {line, count -> print a + line } Groovy Closures
36. def array = [] array = [“one”, “two”, “three”] tab.findAll(){item -> item.size == 3 print it } [1, 2, 3].each(){ print it } def map = [:] map = [one:1, two:2, three:3] assert map.one == map[“one”] def range = 2..5 assert range == [2, 3, 4, 5] Groovy Collections
37. static noNull(Closure c){ String nullLabel = null.toString() NullObject.metaClass.toString = {return ''} c() //set as defaut NullObject.metaClass.toString = {return nullLabel} } cmd([“gmtool”, “admin”, “create” “template”, “device”, “--density=”+density]) >> gmtool admin create template device --density=null noNull{ cmd([“gmtool”, “admin”, “create” “template”, “device”, “--density=”+density]) } >> gmtool admin create template device --density= Groovy Metaclass
38. boolean checkTable(tab) { if(tab?.size() >= 4) return true return false } Groovy Safe Navigation
39. And others Native support for Regex ~/myRegex/ Powerful switch statement switch awesomness { case 1..10: “yeah!” } Operator Overloading 1 + 1 = 1
40. Conclusion You keep focus on business logic Like magic So dynamic, you have to test ! JUnit & Co. So dynamic, so easy to mock JSON-likery
41. References From Java to Groovy http://groovy.dzone.com/news/java-groovy-few-easy-steps By Guillaume Laforge Differences from Java http://groovy.codehaus.org/Differences+from+Java Official documentation http://groovy.codehaus.org/
42. Thank you for your time ! http://eyal.fr SLIDES http://bit.ly/JA2GR