Scala is a general purpose programming language designed to express common programming patterns in a concise, elegant, and type-safe way. It smoothly integrates features of object-oriented and functional languages, enabling Java and other programmers to be more productive." This session is an introduction of Scala for Java developers. Presentation & Fetured Video Included.

1. By : Adi Baron, “Tikal” For Java Programmers

2. "Which Programming Language would you use *now* on top of JVM, except Java?" “ Scala”

3. Since 2003 Runs on JVM Pragmatic High Level Statically Typed Seamless Java interoperability Scalable EPFL Object Oriented Functional Production

5. Growing new types import java.math.BigInteger; public BigInteger factorial (BigInteger x) { if (x == BigInteger. ZERO ) { return BigInteger. ONE ; } return x.multiply(factorial( x.subtract(BigInteger. ONE ))); } def factorial(x: BigInt ): BigInt = if (x == 0) 1 else x * factorial(x - 1)

7. Growing new control constructs val checksum = actor { var sum = 0 loop { receive { case Data (bytes) => sum += hash(bytes) case GetSum (requester) => requester ! sum } } }

8. High-Level boolean nameHasUpperCase = false ; for ( int i = 0; i < name.length(); ++i) { if (Character.isUpperCase(name.charAt(i))) { nameHasUpperCase = true ; break ; } } val nameHasUpperCase = name.exists(_.isUpperCase)

9. Concise public class MyClass { private int id ; private String description ; public MyClass( int id, String description) { this . id = id; this . description = description; } public int getId() { return id ; } public void setId( int id) { this . id = id; } public String getDescription() { return description ; } public void setDescription(String description) { this . description = description; } } class MyClass (id: Int , description: String )

10. What makes it scalable?

11. is Object Oriented

12. Pure Object Oriented 1 + 2 1.+(2) 123.toString

20. Traits

21. Trait trait Dad { private var children: List [ Child ] = Nil def addChild(child: Child ) = children = child :: children def getChildren = children.clone }

22. Base class Man ( val name: String ) extends Human

23. Static mixin composition class Man ( val name: String ) extends Human with Dad val adi = new Man ( “Adi” ) adi.addChild( new Child ( “Yehonatan” )) adi.addChild( new Child ( “Lior” ))

24. Dynamic mixin composition class Man ( val name: String ) extends Human val adi = new Man ( “Adi” ) with Dad adi.addChild( new Child ( “Yehonatan” )) adi.addChild( new Child ( “Lior” ))

25. Composition class MrPotato (name: String ) extends MrPotatoHead with Eyes with Ears with Mouth with Nose with Hands with Hat with Shoes

26. is Functional

29. Functions as parameters scala> val someNumbers = List (-11, -10, -5, 0, 5, 10) someNumbers: List[Int] = List(-11, -10, -5, 0, 5, 10) scala> someNumbers.foreach((x: Int ) => println(x)) -11 -10 -5 0 5 10 scala> someNumbers.filter((x: Int ) => x > 0) res6: List[Int] = List(5, 10)

32. Functions as closures (x: Int ) => x + more // how much more?

33. Functions as closures scala> (x: Int ) => x + more <console>:5: error: not found: value more (x: Int) => x + more ˆ scala> var more = 1 more: Int = 1 scala> val addMore = (x: Int ) => x + more addMore: (Int) => Int = <function> scala> addMore(10) res19: Int = 11

34. Functions as closures def makeIncreaser(more: Int ) = (x: Int ) => x + more scala> val inc1 = makeIncreaser(1) inc1: (Int) => Int = <function> scala> val inc9999 = makeIncreaser(9999) inc9999: (Int) => Int = <function> scala> inc1(10) res24: Int = 11 scala> inc9999(10) res25: Int = 10009

35. Functional Data Structures

37. List - Basics scala> val list = List (1, 2, 3) list: List[Int] = List(1, 2, 3) scala> list.head res0: Int = 1 scala> list.tail res1: List[Int] = List(2, 3) scala> list.isEmpty res2: Boolean = false

38. List – High level operations scala> val list = List (1, 2, 3) list: List[Int] = List(1, 2, 3) scala> list.map(_ + 1) res0: List[Int] = List(2, 3, 4) scala> list.filter(_ < 2) res1: List[Int] = List(1) scala> list.exists(_ == 3) res2: Boolean = true scala> list.drop(2) res3: List[Int] = List(3) scala> list.reverse res4: List[Int] = List(3, 2, 1)

40. & Java

41. Unit Testing - JUnit import junit.framework.TestCase import junit.framework.Assert.assertEquals import junit.framework.Assert.fail import Element.elem class ElementTestCase extends TestCase { def testUniformElement() { val ele = elem( 'x' , 2, 3) assertEquals(2, ele.width) assertEquals(3, ele.height) try { elem('x', -2, 3) fail() } catch { case e: IllegalArgumentException => // expected } } }

42. Unit Testing - TestNG import org.testng.annotations.Test import org.testng.Assert.assertEquals import Element.elem class ElementTests { @ Test def verifyUniformElement() { val ele = elem( 'x' , 2, 3) assertEquals(ele.width, 2) assertEquals(ele.height, 3) } @ Test { val expectedExceptions = Array (classOf[ IllegalArgumentException ]) } def elemShouldThrowIAE() { elem( 'x' , -2, 3) } }

43. Credits

44. Jonas Bonér Scalable Solutions &