Write less JVM code using the power of Groovy Interactive slides at: https://slides.com/hroussel/groovify-your-java-code/

1. Groovify your Java Code
A guide to Groovy syntax for Java coders
By for Coding Dojo 2014
Interactive slides at:
Hervé Vũ Roussel Agile Vietnam
https://slides.com/hroussel/groovify-your-java-code

2. Print / bracket, semicol optional
System.out.println("Hello World!");
println "Hello World!"

3. Return optional
String getCurrentCity() {
return "Ho Chi Minh City";
}
def getCurrentCity() {
"Ho Chi Minh City"
}

4. Try/catch optional
try{
Reader reader = new FileReader("/vietnam-cities.txt")
}
catch(FileNotFoundException e) {
e.printStackTrace()
}
def reader = new FileReader("/vietnam-cities.txt")

5. Duck typing
String s = "Hello";
String c = 'c';
Integer i = new Integer(1);
BigDecimal d = new BigDecimal(1.2);
def s = "Hello"
def c = 'c'
def i = 1
def d = 1.2

6. Strong typing
String s = "Hello";
Character = new Character(‘c’);
Integer i = new Integer(1);
Float d = new Float(1.2);
String s = "Hello"
Character c = 'c'
Integer i = 1
Float f = 1.2

7. Existential operator (Elvis)
if (city != null) {
if (city.getAirport() != null) {
city.getAirport().getCode();
}
}
city?.getAirport()?.getCode()

8. Truth
if (1 != 0)
if (new City() != null)
if ("John".equals(""))
if (["HCMC", "Hanoi"].length > 0)
if (1)
if (city)
if ("John")
if (["HCMC", "Hanoi"])

9. Collections
String [] cities = ["HCMC","Hanoi"];
System.out.println(cities[0]);
Map<String,String> airports = new HashMap<String,String>();
airports.put("SGN", "Ho Chi Minh City");
airports.put("CDG", "Paris");
System.out.println(airports.get("SGN"));
def cities = ["HCMC","Hanoi"]
println cities[0]
def airports = [SGN:"Ho Chi Minh City", CDG:"Paris"]
println airports.SGN

10. Ranges
List<String> alphabet = new ArrayList<String>();
for(int i=0;i<26;i++) {
alphabet.add(Character.toChars(i+97));
}
def alphabet = "a".."z"

11. GString
System.out.println("Hello " + user.name);
println "Hello ${user.name}"

12. Groovy Scripts
public class Script1 {
public static void main(String[] args){
String greeting = "Hello " + args[0];
System.out.println(greeting);
}
}
greeting = "Hello ${args[0]}"
println greeting

13. POGOs
public class City {
private String name;
public String getName() {
return this.name;
}
public String setName(String name) {
this.name = name;
}
}
System.out.println(new City("HCMC").getName());
class City {
String name
}
println new City(name: "HCMC").name

14. Compare objects
a.equals(b);
a.compareTo(b);
a == b
a < b

15. Default parameters
public class Trip {
public Trip(String source, String dest, String type) {
if (type == null)
this.type = "Car";
}
}
new Trip("HCMC", "Vung Tau", null);
class Trip {
Trip(String source, String dest, String type = "Car") {
this.type = type;
}
}
new Trip("HCMC", "Vung Tau")

16. Closures
List result = new ArrayList();
for(city in city) {
if (city.startsWith("H")
result.add(city)
}
cities.findAll { it.startsWith("H") }

17. Closures (cont.)
​class City {
String name
}
def cities = [
new City(name: "Mui Ne"),
new City(name: "Hanoi")
]
cities.collect { it.name + ", VN" } ==
[ "Mui Ne, VN", "Hanoi, VN" ]
cities.any { it.name.indexOf(" ") != -1 } == true
cities.every { it.name.indexOf(" ") == -1 } == false
cities.find { it.name.startsWith("H") }.name == "Hanoi"

19. The End
More on Groovy:
Book: (I didn't write it!)
Slides:
Interactive:
PDF:
Thank you!
Free: Groovy User Guide
Groovy Recipes: Greasing the Wheels of Java
Online compiler/runner
http://slides.com/hroussel
https://www.slideshare.net/hroussel
Hervé Vũ Roussel
http://herveroussel.com

20. Groovify your Java CodeA guide to Groovy syntax for Java coders By Hervé Vũ Roussel for Agile
Vietnam Coding Dojo 2014 Interactive slides at: https://slides.com/hroussel/groovify-your-java-code
Groovify your Java code
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Hervé Roussel
http://www.herveroussel.com hvroussel
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