Modern Programming Made Easy: Using Java, Scala, Groovy, and JavaScript

Appendix A: Java/Groovy ¹

Feature	Java	Groovy
Public class	public class	class
Loops	for(Type it : c){...}	c.each {...}
Lists	List list = Arrays.asList(1,2,3);	def list = [1,2,3]
Maps	Map m = ...; m.put(x,y);	def m = [x: y]
Function def.	void  method(Type  t)  {}	def method(t)  {}
Mutable value	Type t	def t
Immutable value	final Type t	final t
Null safety	(x == null ? null : x.y)	x?.y
Null replacement	(x == null ? "y" : x)	x ?: "y"
Sort	Collections.sort(list)	list.sort()
Wildcard import	import java.util.*;	import java.util.*
Var-args	(String... args)	(String... args)
Type parameters	Class<T>	Class<T>
Equals	a.equals(b)	a == b

No Java Analog

Feature	Groovy
Default closure arg.	it
Default value	def method(t = "yes")
Add method to object	t.metaClass.method   =   {} ...