core-scala: initial commit

core-scala/build.gradle

@@ -0,0 +1,13 @@
+apply plugin: 'scala'
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    compile 'org.scala-lang:scala-library:2.12.6'
+    testCompile 'org.scalatest:scalatest_2.12:3.0.5'
+    testCompile 'junit:junit:4.12'
+}
+
+

core-scala/build.sbt

@@ -0,0 +1,12 @@
+import Dependencies._
+
+lazy val root = (project in file(".")).
+  settings(
+    inThisBuild(List(
+      organization := "com.example",
+      scalaVersion := "2.12.6",
+      version      := "0.1.0-SNAPSHOT"
+    )),
+    name := "core-scala",
+    libraryDependencies += scalaTest % Test
+  )

core-scala/pom.xml

@@ -0,0 +1,111 @@
+<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/maven-v4_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>
+  
+  <properties>
+    <maven.compiler.source>1.8</maven.compiler.source>
+    <maven.compiler.target>1.8</maven.compiler.target>
+    <encoding>UTF-8</encoding>
+    <scala.version>2.12.6</scala.version>
+    <scala.compat.version>2.12</scala.compat.version>
+    <spec2.version>4.2.0</spec2.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.scala-lang</groupId>
+      <artifactId>scala-library</artifactId>
+      <version>${scala.version}</version>
+    </dependency>
+
+    <!-- Test -->
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.12</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.scalatest</groupId>
+      <artifactId>scalatest_${scala.compat.version}</artifactId>
+      <version>3.0.5</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.specs2</groupId>
+      <artifactId>specs2-core_${scala.compat.version}</artifactId>
+      <version>${spec2.version}</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.specs2</groupId>
+      <artifactId>specs2-junit_${scala.compat.version}</artifactId>
+      <version>${spec2.version}</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <sourceDirectory>src/main/scala</sourceDirectory>
+    <testSourceDirectory>src/test/scala</testSourceDirectory>
+    <plugins>
+      <plugin>
+        <!-- see http://davidb.github.com/scala-maven-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>${project.build.directory}/.scala_dependencies</arg>
+              </args>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-surefire-plugin</artifactId>
+        <version>2.21.0</version>
+        <configuration>
+          <!-- Tests will be run with scalatest-maven-plugin instead -->
+          <skipTests>true</skipTests>
+        </configuration>
+      </plugin>
+      <plugin>
+        <groupId>org.scalatest</groupId>
+        <artifactId>scalatest-maven-plugin</artifactId>
+        <version>2.0.0</version>
+        <configuration>
+          <reportsDirectory>${project.build.directory}/surefire-reports</reportsDirectory>
+          <junitxml>.</junitxml>
+          <filereports>TestSuiteReport.txt</filereports>
+          <!-- Comma separated list of JUnit test class names to execute -->
+          <jUnitClasses>samples.AppTest</jUnitClasses>
+        </configuration>
+        <executions>
+          <execution>
+            <id>test</id>
+            <goals>
+              <goal>test</goal>
+            </goals>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+</project>

core-scala/project/Dependencies.scala

@@ -0,0 +1,5 @@
+import sbt._
+
+object Dependencies {
+  lazy val scalaTest = "org.scalatest" %% "scalatest" % "3.0.5"
+}

core-scala/project/build.properties

@@ -0,0 +1 @@
+sbt.version=1.1.6

core-scala/src/main/scala/com/baeldung/examples/ClassExamples.scala

@@ -0,0 +1,31 @@
+package com.baeldung.examples
+
+object ClassExamples extends App {
+
+    import java.time._
+    class Customer(val id:Int, val name:String, dob:LocalDate) {
+
+        private var _age = calculateAge(dob)
+
+        def age = _age // getter
+        def age_= (age:Int) = _age = age //setter
+
+        private def calculateAge(dob:LocalDate) = Period
+                                                .between(dob, LocalDate.now)
+                                                .getYears
+
+        //override def toString: String = s"(id:${id}, name:${name}, age:${age})"
+    }
+    val c = new Customer(1, "Varun Sharma", LocalDate.parse("1980-02-27"))
+    println(c)
+
+    case class Address(addressLn1:String, area:String, city:String, zip:String)
+
+    val address=Address("102, Raycon Lotus Apartment", "AECS Layout", "Bangalore", "560037")
+
+    val anotherAddress = address.copy(addressLn1="41/2, ITPL Road")
+
+    println(address)
+    println(anotherAddress)
+
+}

core-scala/src/main/scala/com/baeldung/examples/CollectionExamples.scala

@@ -0,0 +1,22 @@
+package com.baeldung.examples
+
+object CollectionExamples extends App {
+
+    val aList = List(5, 3, 9, 2) // create a list
+    val sortedAscList = aList.sorted // sort ascending
+    val sortedDescList = aList.sortWith(_ > _) // sort descending
+    val evenList = aList.filter(_%2 == 0) // filter on some condition
+
+    val mySet = Set(10, 20, 5) // create a set
+    val changedSet = mySet + 50 // add an element
+    println(changedSet)
+    val changedSet2 = mySet - 20 // remove an element
+    println(changedSet2)
+
+    val capitals = Map("Japan" -> "Tokyo",
+        "England" -> "London",
+        "India" -> "New Delhi") // create a map
+    val capitalOfJapan = capitals("Japan") // get from map
+    println(capitalOfJapan)
+
+}

core-scala/src/main/scala/com/baeldung/examples/ExceptionHandlingExamples.scala

@@ -0,0 +1,19 @@
+package com.baeldung.examples
+
+object ExceptionHandlingExamples extends App {
+    import java.io._
+    def printLines(filename:String) = {
+        var reader:Option[BufferedReader] = None
+        try {
+            reader = Some(new BufferedReader(new FileReader(new File(filename))))
+            reader.get.lines().forEach(println(_))
+        } catch {
+            case e:FileNotFoundException => println(s"There was no file named ${filename}")
+            case e:Throwable => throw new Exception("Some error occurred", e)
+        } finally {
+            if (reader.isDefined) reader.get.close()
+        }
+    }
+    printLines("test.txt")
+
+}

core-scala/src/main/scala/com/baeldung/examples/FirstClassFunctionExamples.scala

@@ -0,0 +1,17 @@
+package com.baeldung.examples
+
+object FirstClassFunctionExamples extends App {
+
+    def sum(x:Double, y:Double, f:Double => Double) = f(x) + f(y)
+
+    println(sum(3, 4, x => x*x)) // returns 25.0
+
+    println(sum(3, 4, x => x*x*x)) // returns 91.0
+
+    println(sum(3, 4, Math.pow(_, 2))) // returns 25.0
+
+    def max(first:Int, second:Int) = if (first > second) first else second
+
+    println(max(10, -2))
+
+}

core-scala/src/main/scala/com/baeldung/examples/LoopAndCalculationExamples.scala

@@ -0,0 +1,39 @@
+package com.baeldung.examples
+
+object LoopAndCalculationExamples extends App {
+    import CalculationUtils._
+    println(sumWithWhile(Array(10, 20, 30)))
+    println(sumWithFor(Array(10, 20, 30)))
+    println(checkEvenOdd((1 to 10).toArray).toList)
+    println(filterEvens((1 to 10).toArray).toList)
+}
+
+object CalculationUtils {
+
+    def sumWithWhile(values:Array[Int]) = {
+        var sum = 0
+        var i = 0
+        while ( i < values.length) {
+            sum += values(i)
+            i+=1
+        }
+        sum
+    }
+
+    def sumWithFor(values:Array[Int]) = {
+        var sum = 0
+        for (i <- values) {
+            sum += i
+        }
+        sum
+    }
+
+    def checkEvenOdd(values:Array[Int]) = {
+        for (i <- values) yield if (i%2 == 0) "Even" else "Odd"
+    }
+
+    def filterEvens(values:Array[Int]) =
+        for (i <- values if i%2 == 0)
+            yield i
+
+}

core-scala/src/main/scala/com/baeldung/examples/MyApp.scala

@@ -0,0 +1,15 @@
+package com.baeldung.examples
+
+/**
+ * @author ${user.name}
+ */
+object MyApp {
+  
+  def foo(x : Array[String]) = x.foldLeft("")((a,b) => a + b)
+  
+  def main(args : Array[String]) {
+    println( "Hello World!" )
+    println("Number of arguments passed:" + args.length)
+  }
+
+}

core-scala/src/main/scala/com/baeldung/examples/ObjectExamples.scala

@@ -0,0 +1,23 @@
+package com.baeldung.examples
+
+object ObjectExamples extends App {
+
+    import java.time._
+    class Customer(val id:Int, val name:String, private var _age:Int) {
+        def age = this._age
+        def age_= (age:Int) = _age = age
+    }
+    object Customer {
+        def apply(id:Int, name:String, age:Int) = new Customer(id, name, age)
+
+        def apply(id:Int, name:String, dob:LocalDate) = {
+            val p = Period.between(dob, LocalDate.now)
+            new Customer(id, name, p.getYears)
+        }
+    }
+    val c = Customer(1, "Varun Sharma", LocalDate.parse("1980-02-27"))
+
+    c.age = 20
+    println(c.age)
+
+}

core-scala/src/main/scala/com/baeldung/examples/OptionExample.scala

@@ -0,0 +1,12 @@
+package com.baeldung.examples
+
+object OptionExample extends App {
+
+    def minimumEvenNumber(data:Array[Int]) = {
+        val evens = data.filter(_%2 == 0)
+        if (evens.isEmpty) None else Some(evens.min)
+    }
+
+    val minEven = minimumEvenNumber(Array(21, 3, 11, 7)).getOrElse(0)
+    println(minEven)
+}

core-scala/src/main/scala/com/baeldung/examples/PatternMatchingExample.scala

@@ -0,0 +1,22 @@
+package com.baeldung.examples
+
+object PatternMatchingExample extends App {
+
+  abstract class Item
+  case class Book(title:String, author:String, price:Double) extends Item
+  case class MusicCD(title:String, genre:String, price:Double) extends Item
+
+  def describe(item:Item) = item match {
+
+    case b:Book if b.price > 1000 => println(s"The book ${b.title} is expensive")
+
+    case b:Book => println(s"The book ${b.title} is written by ${b.author}.")
+
+    case MusicCD(title, "Jazz", _) => println(s"This is a CD of Jazz music.")
+
+    case _ => println("Unknown Item")
+
+  }
+
+  describe(Book("Half Girlfriend", "Chetan Bhagat", 100))
+}

core-scala/src/main/scala/com/baeldung/examples/TraitExample.scala

@@ -0,0 +1,23 @@
+package com.baeldung.examples
+
+import java.io._
+
+object TraitExample extends App {
+
+    trait Loggable {
+        val logger:PrintStream
+        def getPrefix():String
+        def log(message:String) = logger.println(s"[${getPrefix()}]:${message}")
+    }
+    object CustomerService extends Loggable {
+        override val logger = System.out
+        override def getPrefix(): String = "CustomerService"
+        def retrieve(id:String) = {
+            log(s"Retrieve with id ${id} called")
+            // Code to retrieve Customer from DB
+        }
+    }
+
+    CustomerService.retrieve("C100")
+
+}

core-scala/src/main/scala/com/baeldung/examples/TupleExamples.scala

@@ -0,0 +1,18 @@
+package com.baeldung.examples
+
+object TupleExamples extends App {
+
+    val empSal:(String, Int) = ("David", 10000)
+
+    def getMaxMinSalary(empSal:Array[(String, Int)]) = {
+        val minEmpSal = empSal.minBy(empSal => empSal._2)
+        val maxEmpSal = empSal.maxBy(empSal => empSal._2)
+        (maxEmpSal._2, minEmpSal._2)
+    }
+    val empSalArr = Array(("David", 12000), ("Maria", 15000),
+            ("Elisa", 11000), ("Adam", 8000))
+
+    val (maxSalary, minSalary) = getMaxMinSalary(empSalArr)
+    println("Max Salary: " + maxSalary + " and Min Salary: " + minSalary)
+
+}

core-scala/src/main/scala/com/baeldung/examples/VariableDeclaration.scala

@@ -0,0 +1,24 @@
+package com.baeldung.examples
+
+object VariableDeclaration extends App {
+
+    val x:Int = 0
+    var friend:String = "David"
+    lazy val greet = "Hello" + friend
+    val data = Array(2, 4, 5)
+
+    printHelloWorld()
+    println(sum(10, 20))
+
+    def printHelloWorld():Unit = {
+        println("Hello World")
+    }
+
+    def sum(x:Int, y:Int) = x + y
+
+    def sayGreeting(to:String, greet:String="Hi", message:String = "How are you?") = println(greet + " " + to + ", " + message)
+
+    sayGreeting(to="David", message="How are you doing?")
+    sayGreeting(greet="Hello", to="Maria")
+
+}

core-scala/src/test/scala/samples/junit.scala

@@ -0,0 +1,17 @@
+package samples
+
+import org.junit._
+import Assert._
+
+@Test
+class AppTest {
+
+    @Test
+    def testOK() = assertTrue(true)
+
+//    @Test
+//    def testKO() = assertTrue(false)
+
+}
+
+

core-scala/src/test/scala/samples/scalatest.scala

@@ -0,0 +1,108 @@
+/*
+ * Copyright 2001-2009 Artima, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package samples
+
+/*
+ScalaTest facilitates different styles of testing by providing traits you can mix
+together to get the behavior and syntax you prefer.  A few examples are
+included here.  For more information, visit:
+
+http://www.scalatest.org/
+
+One way to use ScalaTest is to help make JUnit or TestNG tests more
+clear and concise. Here's an example:
+*/
+import scala.collection._
+import org.scalatest.Assertions
+import org.junit.Test
+
+class StackSuite extends Assertions {
+
+  @Test def stackShouldPopValuesIinLastInFirstOutOrder() {
+    val stack = new mutable.ArrayStack[Int]
+    stack.push(1)
+    stack.push(2)
+    assert(stack.pop() === 2)
+    assert(stack.pop() === 1)
+  }
+
+  @Test def stackShouldThrowRuntimeExceptionIfAnEmptyArrayStackIsPopped() {
+    val emptyStack = new mutable.ArrayStack[String]
+    intercept[RuntimeException] {
+      emptyStack.pop()
+    }
+  }
+}
+
+/*
+Here's an example of a FunSuite with Matchers mixed in:
+*/
+import org.scalatest.FunSuite
+import org.scalatest.Matchers
+
+import org.junit.runner.RunWith
+import org.scalatest.junit.JUnitRunner
+@RunWith(classOf[JUnitRunner])
+class ListSuite extends FunSuite with Matchers {
+
+  test("An empty list should be empty") {
+    List() should be ('empty)
+    Nil should be ('empty)
+  }
+
+  test("A non-empty list should not be empty") {
+    List(1, 2, 3) should not be ('empty)
+    List("fee", "fie", "foe", "fum") should not be ('empty)
+  }
+
+  test("A list's length should equal the number of elements it contains") {
+    List() should have length (0)
+    List(1, 2) should have length (2)
+    List("fee", "fie", "foe", "fum") should have length (4)
+  }
+}
+
+/*
+ScalaTest also supports the behavior-driven development style, in which you
+combine tests with text that specifies the behavior being tested. Here's
+an example whose text output when run looks like:
+
+A Map
+- should only contain keys and values that were added to it
+- should report its size as the number of key/value pairs it contains
+*/
+import org.scalatest.FunSpec
+
+class ExampleSpec extends FunSpec {
+
+  describe("An ArrayStack") {
+
+    it("should pop values in last-in-first-out order") {
+      val stack = new mutable.ArrayStack[Int]
+      stack.push(1)
+      stack.push(2)
+      assert(stack.pop() === 2)
+      assert(stack.pop() === 1)
+    }
+
+    it("should throw RuntimeException if an empty array stack is popped") {
+      val emptyStack = new mutable.ArrayStack[Int]
+      intercept[RuntimeException] {
+        emptyStack.pop()
+      }
+    }
+  }
+}

core-scala/src/test/scala/samples/specs.scala

@@ -0,0 +1,31 @@
+package samples
+
+import org.junit.runner.RunWith
+import org.specs2.mutable._
+import org.specs2.runner._
+  
+
+/**
+ * Sample specification.
+ * 
+ * This specification can be executed with: scala -cp <your classpath=""> ${package}.SpecsTest
+ * Or using maven: mvn test
+ *
+ * For more information on how to write or run specifications, please visit: 
+ *   http://etorreborre.github.com/specs2/guide/org.specs2.guide.Runners.html
+ *
+ */
+@RunWith(classOf[JUnitRunner])
+class MySpecTest extends Specification {
+  "The 'Hello world' string" should {
+    "contain 11 characters" in {
+      "Hello world" must have size(11)
+    }
+    "start with 'Hello'" in {
+      "Hello world" must startWith("Hello")
+    }
+    "end with 'world'" in {
+      "Hello world" must endWith("world")
+    }
+  }
+}

core-scala/test.txt

@@ -0,0 +1,4 @@
+Hi,
+This is the lines
+from the test file.
+Thanks.