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Merge pull request #5416 from chandra1123/BAEL-2041 

Bael-2041 Introduction to Scala
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Eric Martin 2018-10-28 10:29:09 -05:00 committed by GitHub
parent 331b2746ad 464189ff4e
commit b57a14db36
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14 changed files with 400 additions and 1 deletions
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2
.gitignore vendored
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@ -64,3 +64,5 @@ jmeter/src/main/resources/*-JMeter.csv
**/out-tsc
**/nbproject/
**/nb-configuration.xml
core-scala/.cache-main
core-scala/.cache-tests

53
core-scala/pom.xml Normal file
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<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>core-scala</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<parent>
<groupId>com.baeldung</groupId>
<artifactId>parent-modules</artifactId>
<version>1.0.0-SNAPSHOT</version>
</parent>
<dependencies>
<dependency>
<groupId>org.scala-lang</groupId>
<artifactId>scala-library</artifactId>
<version>${scala.version}</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src/main/scala</sourceDirectory>
<testSourceDirectory>src/test/scala</testSourceDirectory>
<plugins>
<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
<version>3.3.2</version>
<executions>
<execution>
<goals>
<goal>compile</goal>
<goal>testCompile</goal>
</goals>
<configuration>
<args>
<arg>-dependencyfile</arg>
<arg>${project.build.directory}/.scala_dependencies</arg>
</args>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
<properties>
<scala.version>2.12.7</scala.version>
</properties>
</project>

44
core-scala/src/main/scala/com/baeldung/scala/ControlStructuresDemo.scala Normal file
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package com.baeldung.scala
/**
* Sample code demonstrating the various control structured.
*
* @author Chandra Prakash
*
*/
object ControlStructuresDemo {
def gcd(x : Int, y : Int) : Int = {
if (y == 0) x else gcd(y, x % y)
}
def gcdIter(x : Int, y : Int) : Int = {
var a = x
var b = y
while (b > 0) {
a = a % b
val t = a
a = b
b = t
}
a
}
def rangeSum(a : Int, b : Int) = {
var sum = 0;
for (i <- a to b) {
sum += i
}
sum
}
def factorial(a : Int) : Int = {
var result = 1;
var i = 1;
do {
result *= i
i = i + 1
} while (i <= a)
result
}
}

27
core-scala/src/main/scala/com/baeldung/scala/Employee.scala Normal file
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package com.baeldung.scala
/**
* Sample Code demonstrating a class.
*
* @author Chandra Prakash
*
*/
class Employee(val name : String,
var salary : Int,
annualIncrement : Int = 20) {
def incrementSalary() : Unit = {
salary += annualIncrement
}
override def toString =
s"Employee(name=$name, salary=$salary)"
}
/**
* A Trait which will make the toString return upper case value.
*/
trait UpperCasePrinter {
override def toString = super.toString toUpperCase
}

6
core-scala/src/main/scala/com/baeldung/scala/HelloWorld.scala Normal file
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@ -0,0 +1,6 @@
package com.baeldung.scala
object HelloWorld extends App {
println("Hello World!")
args foreach println
}

27
core-scala/src/main/scala/com/baeldung/scala/HigherOrderFunctions.scala Normal file
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package com.baeldung.scala
/**
* Sample higher order functions.
*
* @author Chandra Prakash
*
*/
object HigherOrderFunctions {
def mapReduce(r : (Int, Int) => Int,
i : Int,
m : Int => Int,
a : Int, b : Int) = {
def iter(a : Int, result : Int) : Int = {
if (a > b) result
else iter(a + 1, r(m(a), result))
}
iter(a, i)
}
def whileLoop(condition : => Boolean)(body : => Unit) : Unit =
if (condition) {
body
whileLoop(condition)(body)
}
}

34
core-scala/src/main/scala/com/baeldung/scala/IntSet.scala Normal file
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package com.baeldung.scala
/**
* An abstract class for set of integers and its implementation.
*
* @author Chandra Prakash
*
*/
abstract class IntSet {
// add an element to the set
def incl(x : Int) : IntSet
// whether an element belongs to the set
def contains(x : Int) : Boolean
}
class EmptyIntSet extends IntSet {
def contains(x : Int) : Boolean = false
def incl(x : Int) =
new NonEmptyIntSet(x, this)
}
class NonEmptyIntSet(val head : Int, val tail : IntSet)
extends IntSet {
def contains(x : Int) : Boolean =
head == x || (tail contains x)
def incl(x : Int) : IntSet =
if (this contains x) this
else new NonEmptyIntSet(x, this)
}

33
core-scala/src/main/scala/com/baeldung/scala/Utils.scala Normal file
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package com.baeldung.scala
/**
* Some utility methods.
*
* @author Chandra Prakash
*
*/
object Utils {
def average(x : Double, y : Double) = (x + y) / 2
def randomLessThan(d : Double) = {
var random = 0d
do {
random = Math.random()
} while (random >= d)
random
}
def power(x : Int, y : Int) : Int = {
def powNested(i : Int, accumulator : Int) : Int = {
if (i <= 0) accumulator
else powNested(i - 1, x * accumulator)
}
powNested(y, 1)
}
def fibonacci(n : Int) : Int = n match {
case 0 | 1 => 1
case x if x > 1 =>
fibonacci(x - 1) + fibonacci(x - 2)
}
}

33
core-scala/src/test/scala/com/baeldung/scala/ControlStructuresDemoUnitTest.scala Normal file
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package com.baeldung.scala
import com.baeldung.scala.ControlStructuresDemo._
import org.junit.Test
import org.junit.Assert.assertEquals
class ControlStructuresDemoUnitTest {
@Test
def givenTwoIntegers_whenGcdCalled_thenCorrectValueReturned = {
assertEquals(3, gcd(15, 27))
}
@Test
def givenTwoIntegers_whenGcdIterCalled_thenCorrectValueReturned = {
assertEquals(3, gcdIter(15, 27))
}
@Test
def givenTwoIntegers_whenRangeSumcalled_thenCorrectValueReturned = {
assertEquals(55, rangeSum(1, 10))
}
@Test
def givenPositiveInteger_whenFactorialInvoked_thenCorrectValueReturned = {
assertEquals(720, factorial(6))
}
@Test
def whenFactorialOf0Invoked_then1Returned = {
assertEquals(1, factorial(0))
}
}

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core-scala/src/test/scala/com/baeldung/scala/EmployeeUnitTest.scala Normal file
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package com.baeldung.scala
import org.junit.Assert.assertEquals
import org.junit.Test
class EmployeeUnitTest {
@Test
def whenEmployeeSalaryIncremented_thenCorrectSalary = {
val employee = new Employee("John Doe", 1000)
employee.incrementSalary()
assertEquals(1020, employee.salary)
}
@Test
def givenEmployee_whenToStringCalled_thenCorrectStringReturned = {
val employee = new Employee("John Doe", 1000)
assertEquals("Employee(name=John Doe, salary=1000)", employee.toString)
}
@Test
def givenEmployeeWithTrait_whenToStringCalled_thenCorrectStringReturned = {
val employee =
new Employee("John Doe", 1000) with UpperCasePrinter
assertEquals("EMPLOYEE(NAME=JOHN DOE, SALARY=1000)", employee.toString)
}
}

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core-scala/src/test/scala/com/baeldung/scala/HigherOrderFunctionsUnitTest.scala Normal file
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package com.baeldung.scala
import org.junit.Assert.assertEquals
import org.junit.Test
import HigherOrderFunctions.mapReduce
class HigherOrderFunctionsUnitTest {
@Test
def whenCalledWithSumAndSquareFunctions_thenCorrectValueReturned = {
def square(x : Int) = x * x
def sum(x : Int, y : Int) = x + y
def sumSquares(a : Int, b : Int) =
mapReduce(sum, 0, square, a, b)
assertEquals(385, sumSquares(1, 10))
}
@Test
def whenComputingSumOfSquaresWithAnonymousFunctions_thenCorrectValueReturned = {
def sumSquares(a : Int, b : Int) =
mapReduce((x, y) => x + y, 0, x => x * x, a, b)
assertEquals(385, sumSquares(1, 10))
}
@Test
def givenCurriedFunctions_whenInvoked_thenCorrectValueReturned = {
// a curried function
def sum(f : Int => Int)(a : Int,
b : Int) : Int =
if (a > b) 0 else f(a) + sum(f)(a + 1, b)
// another curried function
def mod(n : Int)(x : Int) = x % n
// application of a curried function
assertEquals(1, mod(5)(6))
// partial application of curried function
// trailing underscore is required to make function type explicit
val sumMod5 = sum(mod(5)) _
assertEquals(10, sumMod5(6, 10))
}
}

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core-scala/src/test/scala/com/baeldung/scala/IntSetUnitTest.scala Normal file
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package com.baeldung.scala
import scala.Range
import org.junit.Assert.assertFalse
import org.junit.Test
class IntSetUnitTest {
@Test
def givenSetof1To10_whenContains11Called_thenFalse = {
// Set up a set containing integers 1 to 10.
val set1To10 =
Range(1, 10)
.foldLeft(new EmptyIntSet() : IntSet) {
(x, y) => x incl y
}
assertFalse(set1To10 contains 11)
}
}

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core-scala/src/test/scala/com/baeldung/scala/UtilsUnitTest.scala Normal file
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package com.baeldung.scala
import org.junit.Assert.assertEquals
import org.junit.Assert.assertTrue
import org.junit.Test
import Utils.average
import Utils.fibonacci
import Utils.power
import Utils.randomLessThan
class UtilsUnitTest {
@Test
def whenAverageCalled_thenCorrectValueReturned() = {
assertEquals(15.0, average(10, 20), 1e-5)
}
@Test
def whenRandomLessThanInvokedWithANumber_thenARandomLessThanItReturned = {
val d = 0.1
assertTrue(randomLessThan(d) < d)
}
@Test
def whenPowerInvokedWith2And3_then8Returned = {
assertEquals(8, power(2, 3))
}
@Test
def whenFibonacciCalled_thenCorrectValueReturned = {
assertEquals(1, fibonacci(0))
assertEquals(1, fibonacci(1))
assertEquals(fibonacci(6),
fibonacci(4) + fibonacci(5))
}
}

1
pom.xml
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@ -386,6 +386,7 @@
<module>guava-modules/guava-21</module>
<module>guice</module>
<module>disruptor</module>
<module>core-scala</module>
<module>spring-static-resources</module>
<module>hazelcast</module>
<module>persistence-modules/hbase</module>