Getting groovy (ODP)
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The document discusses how Groovy provides a simpler and more concise way to work with Java code for tasks like file input/output, XML parsing, and configuration compared to Java and other languages like Perl and Ruby. It highlights Groovy features like built-in support for closures, the Elvis operator, date formatting, and ExpandoMetaClass that allow for more readable and expressive code.
![XML Parsing <langs type="current"> <language>Perl</language> <language>Java</language> <language>Groovy</language> </langs> public class ParseXml { public static void main(String[] args) { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder db = dbf.newDocumentBuilder(); Document doc = db.parse(“langs.xml"); Element langs = doc.getDocumentElement(); System.out.println("type = " + langs.getAttribute("type")); NodeList list = langs.getElementsByTagName("language"); for(int i=0; i < list.getLength(); i++) { Element language = (Element) list.item(i); System.out.println(language.getTextContent()); } } catch(ParserConfigurationException pce) { pce.printStackTrace(); } catch(SAXException se) { se.printStackTrace(); } catch(IOException ioe) { ioe.printStackTrace(); } } } }](https://image.slidesharecdn.com/gettinggroovy-110916153728-phpapp01/85/Getting-groovy-ODP-23-320.jpg)
Getting groovy (ODP)
- 2. Two Worlds Collide Java Perl
- 3. Two Worlds Collide Java Perl
- 4. Two Worlds Collide Java Perl
- 5. Two Worlds Collide Java Perl
- 6. JVM Languages Java JRuby Jython
- 7. JVM Languages Java JRuby Jython
- 8. JVM Languages Java JRuby Jython Groovy
- 9. What ’ s wrong with Java anyway?
- 10. Slurping files in Perl
- 11. Slurping files in Perl my $fh = open '<', $filename; local $/ = undef; my $contents = <$fh>;
- 12. Slurping files in Perl my $fh = open '<', $filename; local $/ = undef; my $contents = <$fh>; Slurping in Ruby
- 13. Slurping files in Perl my $fh = open '<', $filename; local $/ = undef; my $contents = <$fh>; file = File.open(filename, "rb") contents = file.read Slurping in Ruby
- 14. Java?
- 15. Java? StringBuilder contents = new StringBuilder(); try { BufferedReader input = new BufferedReader(new FileReader(aFile)); try { String line = null; while ( (line = input.readLine()) != null) { contents.append(line); contents.append(lineSeparator); } } finally { input.close(); } } catch (IOException ex) { ex.printStackTrace(); } ... = contents.toString();
- 18. What would Groovy do?
- 19. What would Groovy do? def contents = new File(filename) …
- 20. What would Groovy do? def contents = new File(filename) .text
- 21. XML Parsing <langs type="current"> <language>Perl</language> <language>Java</language> <language>Groovy</language> </langs>
- 22. XML Parsing <langs type="current"> <language>Perl</language> <language>Java</language> <language>Groovy</language> </langs> import org.w3c.dom.*; import org.xml.sax.SAXException; import javax.xml.parsers.*; import java.io.IOException;
- 23. XML Parsing <langs type="current"> <language>Perl</language> <language>Java</language> <language>Groovy</language> </langs> public class ParseXml { public static void main(String[] args) { DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); try { DocumentBuilder db = dbf.newDocumentBuilder(); Document doc = db.parse(“langs.xml"); Element langs = doc.getDocumentElement(); System.out.println("type = " + langs.getAttribute("type")); NodeList list = langs.getElementsByTagName("language"); for(int i=0; i < list.getLength(); i++) { Element language = (Element) list.item(i); System.out.println(language.getTextContent()); } } catch(ParserConfigurationException pce) { pce.printStackTrace(); } catch(SAXException se) { se.printStackTrace(); } catch(IOException ioe) { ioe.printStackTrace(); } } } }
- 24. XML Parsing in Groovy <langs type="current"> <language>Perl</language> <language>Java</language> <language>Groovy</language> </langs>
- 25. XML Parsing in Groovy <langs type="current"> <language>Perl</language> <language>Java</language> <language>Groovy</language> </langs> def langs = new XmlSlurper().parse("langs.xml") println langs.@type langs.language.each { elem -> println elem }
- 26. XML Parsing in Groovy <langs type="current"> <language>Perl</language> <language>Java</language> <language>Groovy</language> </langs> def langs = new XmlSlurper().parse("langs.xml") println langs.@type langs.language.each { println it }
- 27. Closures (1..10).each {|i| print i, "\n" } (1..10).each {i -> println i } Ruby Groovy
- 28. Configuration def config = new ConfigSlurper().parse(...) def config = new ConfigSlurper() .parse(new File("config.groovy").toURL()) assert config.foo.port == 80 assert config.foo.bar.baz.some.thing == "burp" foo { port = 80 bar { baz { some.thing = "burp" } } }
- 29. Runtime Environments foo.bar = "baz" something.else = 99 environments { development { port = 8181 db = "devdb" } test { port = 8080 db = "testdb" } production { port = 80 db = "proddb" } } ConfigSlurper("production")
- 30. More short-hand def result = a ? a : b The Elvis operator def result = a ?: b
- 31. More short-hand new Date().format('yyyy-MM-dd') Date formatting
- 32. ExpandoMetaClass Number.metaClass.getProperty = { propertyName -> if (propertyName == 'percent') { delegate / 100 } else { delegate } } println 20.percent // 0.20 println 17.5.percent // 0.175
Editor's Notes
- #3: Perl and Java really don't get on
- #6: Like Leeds United, Perl used to be incredibly popular, faded a bit, suddenly looked promising about a decade ago, and fans have been waiting ever since then for a big comeback. In the meantime, some of the star players have moved on to better things.
- #7: So no JVM Perl yet.
- #8: Integration between Java and most other JVM languages is usually in only one direction. It's easy to use Java libraries in jython/jruby, but harder to use java/jython code elsewhere in Java.
- #9: Groovy generates Java classes, which can be packaged and used in Java alongside other jars.
- #26: Wait – that’s too verbose…
- #27: “ it ” is shorthand – a default parameter, like Perl’s $ _
- #28: “ it ” is shorthand – a default parameter, like Perl’s $ _