SCALA-268 (#1760)

* SCALA-268
Scala CSV Read/Write

* Naming convention fixed

Author: maenolis

Diff for: build.sbt

@@ -442,7 +442,11 @@ lazy val scala_libraries = (project in file("scala-libraries"))
       "org.apache.logging.log4j" % "log4j-core" % "2.24.3" % Runtime,
       "com.typesafe.scala-logging" %% "scala-logging" % "3.9.5",
       "software.amazon.awssdk" % "s3" % "2.25.9",
-      "com.github.seratch" %% "awscala" % "0.9.2"
+      "com.github.seratch" %% "awscala" % "0.9.2",
+      "com.opencsv" % "opencsv" % "5.9",
+      "com.github.tototoshi" %% "scala-csv" % "2.0.0",
+      "org.apache.commons" % "commons-csv" % "1.12.0"
+
     ),
     libraryDependencies ++= Seq(
       "org.playframework" %% "play-slick" % LibraryVersions.playSlickVersion,

Diff for: scala-libraries/src/main/resources/persons.csv

@@ -0,0 +1,4 @@
+id,name
+1,Jim
+2,Bob
+3,Mary

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/reader/ApacheCommonsCSVReader.scala

@@ -0,0 +1,24 @@
+package com.baeldung.csv.reader
+
+import org.apache.commons.csv.CSVFormat
+
+import java.io.{File, FileInputStream, InputStreamReader}
+import scala.jdk.CollectionConverters.IterableHasAsScala
+
+class ApacheCommonsCSVReader extends CommaSeparatedValuesReader {
+
+  override def read(file: File): CSVReadDigest = {
+    val in = new InputStreamReader(new FileInputStream(file))
+    val csvParser = CSVFormat.DEFAULT
+      .builder()
+      .setHeader()
+      .build()
+      .parse(in)
+    val result = CSVReadDigest(
+      csvParser.getHeaderNames.asScala.toSeq,
+      csvParser.getRecords.asScala.map(r => r.values().toSeq).toSeq
+    )
+    csvParser.close()
+    result
+  }
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/reader/CSVReaders.scala

@@ -0,0 +1,23 @@
+package com.baeldung.csv.reader
+
+import java.io.File
+
+object CSVReaders {
+
+  def main(args: Array[String]): Unit = {
+
+    val apacheCommonsCSVReader = new ApacheCommonsCSVReader
+    val simpleCSVReader = new SimpleCSVReader
+    val scalaCSVReader = new ScalaCSVReader
+    val openCSVReader = new OpenCSVReader
+
+    val file = new File(getClass.getResource("/persons.csv").getFile)
+
+    println(apacheCommonsCSVReader.read(file))
+    println(simpleCSVReader.read(file))
+    println(scalaCSVReader.read(file))
+    println(openCSVReader.read(file))
+
+  }
+
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/reader/CommaSeparatedValuesReader.scala

@@ -0,0 +1,10 @@
+package com.baeldung.csv.reader
+
+import java.io.File
+
+case class CSVReadDigest(headers: Seq[String], rows: Seq[Seq[String]])
+trait CommaSeparatedValuesReader {
+
+  def read(file: File): CSVReadDigest
+
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/reader/OpenCSVReader.scala

@@ -0,0 +1,35 @@
+package com.baeldung.csv.reader
+
+import com.opencsv.CSVReader
+
+import java.io.{File, FileInputStream, InputStreamReader}
+import scala.annotation.tailrec
+
+class OpenCSVReader extends CommaSeparatedValuesReader {
+
+  override def read(file: File): CSVReadDigest = {
+
+    val reader = new CSVReader(
+      new InputStreamReader(new FileInputStream(file))
+    )
+
+    @tailrec
+    def readLinesRecursively(
+      currentReader: CSVReader,
+      result: Seq[Seq[String]]
+    ): Seq[Seq[String]] = {
+      currentReader.readNext() match {
+        case null => result
+        case line => readLinesRecursively(currentReader, result :+ line.toSeq)
+      }
+    }
+
+    val csvLines = readLinesRecursively(reader, List())
+    reader.close()
+
+    CSVReadDigest(
+      csvLines.head,
+      csvLines.tail
+    )
+  }
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/reader/ScalaCSVReader.scala

@@ -0,0 +1,15 @@
+package com.baeldung.csv.reader
+
+import com.github.tototoshi.csv.CSVReader
+
+import java.io.File
+
+class ScalaCSVReader extends CommaSeparatedValuesReader {
+
+  override def read(file: File): CSVReadDigest = {
+    val reader = CSVReader.open(file)
+    val all = reader.all()
+    reader.close()
+    CSVReadDigest(all.head, all.tail)
+  }
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/reader/SimpleCSVReader.scala

@@ -0,0 +1,36 @@
+package com.baeldung.csv.reader
+
+import java.io.{BufferedReader, File, FileInputStream, InputStreamReader}
+import scala.annotation.tailrec
+
+class SimpleCSVReader extends CommaSeparatedValuesReader {
+
+  override def read(file: File): CSVReadDigest = {
+    val in = new InputStreamReader(new FileInputStream(file))
+    val bufferedReader = new BufferedReader(in)
+
+    @tailrec
+    def readLinesRecursively(
+      currentBufferedReader: BufferedReader,
+      result: Seq[Seq[String]]
+    ): Seq[Seq[String]] = {
+      currentBufferedReader.readLine() match {
+        case null => result
+        case line =>
+          readLinesRecursively(
+            currentBufferedReader,
+            result :+ line.split(",").toSeq
+          )
+      }
+    }
+
+    val csvLines = readLinesRecursively(bufferedReader, List())
+
+    bufferedReader.close()
+
+    CSVReadDigest(
+      csvLines.head,
+      csvLines.tail
+    )
+  }
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/writer/ApacheCommonsCSVWriter.scala

@@ -0,0 +1,25 @@
+package com.baeldung.csv.writer
+import org.apache.commons.csv.{CSVFormat, CSVPrinter}
+
+import java.io.{File, FileWriter}
+import scala.util.Try
+
+class ApacheCommonsCSVWriter extends CommaSeparatedValuesWriter {
+
+  override def write(
+    file: File,
+    headers: Seq[String],
+    rows: Seq[Seq[String]]
+  ): Try[Unit] = Try {
+
+    val csvFormat = CSVFormat.DEFAULT
+      .builder()
+      .setHeader(headers: _*)
+      .build()
+
+    val out = new FileWriter(file)
+    val printer = new CSVPrinter(out, csvFormat)
+    rows.foreach(row => printer.printRecord(row: _*))
+    printer.close()
+  }
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/writer/CommaSeparatedValuesWriter.scala

@@ -0,0 +1,14 @@
+package com.baeldung.csv.writer
+
+import java.io.File
+import scala.util.Try
+
+trait CommaSeparatedValuesWriter {
+
+  def write(
+    file: File,
+    headers: Seq[String],
+    rows: Seq[Seq[String]]
+  ): Try[Unit]
+
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/writer/CsvWriters.scala

@@ -0,0 +1,51 @@
+package com.baeldung.csv.writer
+
+import java.io.File
+import scala.util.{Failure, Success, Try}
+
+object CsvWriters {
+
+  def main(args: Array[String]): Unit = {
+
+    val fileName = "foo.csv"
+    val headers = List("id", "name")
+    val rows = List(
+      List("1", "Manolis"),
+      List("2", "Thanasis"),
+      List("3", "Stefanos")
+    )
+
+    val simpleCSVWriter = new SimpleCSVWriter
+    val openCSVWriter = new OpenCSVWriter
+    val scalaCSVWriter = new ScalaCSVWriter
+    val apacheCommonsCSVWriter = new ApacheCommonsCSVWriter
+
+    handleFailure(
+      simpleCSVWriter.write(new File(s"simple-$fileName"), headers, rows)
+    )
+    handleFailure(
+      openCSVWriter.write(new File(s"openCSV-$fileName"), headers, rows)
+    )
+    handleFailure(
+      scalaCSVWriter.write(new File(s"scalaCSV-$fileName"), headers, rows)
+    )
+    handleFailure(
+      apacheCommonsCSVWriter.write(
+        new File(s"apacheCommons-$fileName"),
+        headers,
+        rows
+      )
+    )
+  }
+
+  private def handleFailure(tryWrite: Try[Unit]): Unit = {
+    tryWrite match {
+      case Success(_) =>
+      case Failure(exception) =>
+        println(
+          s"Something went wrong during CSV writing: ${exception.getMessage}"
+        )
+    }
+  }
+
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/writer/OpenCSVWriter.scala

@@ -0,0 +1,26 @@
+package com.baeldung.csv.writer
+
+import com.opencsv.CSVWriter
+
+import java.io.{BufferedWriter, File, FileWriter}
+import scala.jdk.CollectionConverters.IterableHasAsJava
+import scala.util.Try
+
+class OpenCSVWriter extends CommaSeparatedValuesWriter {
+
+  override def write(
+    file: File,
+    headers: Seq[String],
+    rows: Seq[Seq[String]]
+  ): Try[Unit] = Try(
+    new CSVWriter(new BufferedWriter(new FileWriter(file)))
+  ).flatMap((csvWriter: CSVWriter) =>
+    Try {
+      csvWriter.writeAll(
+        (headers +: rows).map(_.toArray).asJava,
+        false
+      )
+      csvWriter.close()
+    }
+  )
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/writer/ScalaCSVWriter.scala

@@ -0,0 +1,20 @@
+package com.baeldung.csv.writer
+
+import com.github.tototoshi.csv.CSVWriter
+
+import java.io.File
+import scala.util.Try
+
+class ScalaCSVWriter extends CommaSeparatedValuesWriter {
+
+  override def write(
+    file: File,
+    headers: Seq[String],
+    rows: Seq[Seq[String]]
+  ): Try[Unit] = Try {
+    val writer = CSVWriter.open(file)
+    writer.writeRow(headers)
+    writer.writeAll(rows)
+    writer.close()
+  }
+}

Diff for: scala-libraries/src/main/scala/com/baeldung/csv/writer/SimpleCSVWriter.scala

@@ -0,0 +1,19 @@
+package com.baeldung.csv.writer
+
+import java.io.{File, PrintWriter}
+import scala.util.Try
+
+class SimpleCSVWriter extends CommaSeparatedValuesWriter {
+
+  override def write(
+    file: File,
+    headers: Seq[String],
+    rows: Seq[Seq[String]]
+  ): Try[Unit] = Try {
+    val writer = new PrintWriter(file)
+    writer.println(headers.mkString(","))
+    rows.foreach(row => writer.println(row.mkString(",")))
+    writer.close()
+  }
+
+}

Diff for: scala-libraries/src/test/scala/com/baeldung/csv/reader/ScalaCSVReadersUnitTest.scala

@@ -0,0 +1,63 @@
+package com.baeldung.csv.reader
+
+import org.scalatest.matchers.should
+import org.scalatest.wordspec.AnyWordSpec
+
+import java.io.{File, PrintWriter}
+import java.nio.file.{Files, Path}
+import java.util.UUID
+
+class ScalaCSVReadersUnitTest extends AnyWordSpec with should.Matchers {
+
+  "SimpleCSVReader" should {
+    "read a csv file" in {
+      commonTestBody(new SimpleCSVReader, randomTmpFile().toFile)
+    }
+  }
+
+  "ScalaCSVReader" should {
+    "read a csv file" in {
+      commonTestBody(new ScalaCSVReader, randomTmpFile().toFile)
+    }
+  }
+
+  "OpenCSVReader" should {
+    "read a csv file" in {
+      commonTestBody(new OpenCSVReader, randomTmpFile().toFile)
+    }
+  }
+
+  "ApacheCommonsCSVReader" should {
+    "read a csv file" in {
+      commonTestBody(new ApacheCommonsCSVReader, randomTmpFile().toFile)
+    }
+  }
+
+  private def commonTestBody(
+    testee: CommaSeparatedValuesReader,
+    file: File
+  ): Unit = {
+    val result = testee.read(file)
+    assert(result.headers === List("column1", "column2"))
+    assert(
+      result.rows === List(
+        List("1.1", "1.2"),
+        List("2.1", "2.2")
+      )
+    )
+  }
+
+  private def randomTmpFile(): Path = {
+    val path = Files.createTempFile(
+      s"persons-${UUID.randomUUID().toString.take(8)}",
+      "csv"
+    )
+    val writer = new PrintWriter(path.toFile)
+    writer.println(List("column1", "column2").mkString(","))
+    writer.println(List("1.1", "1.2").mkString(","))
+    writer.println(List("2.1", "2.2").mkString(","))
+    writer.close()
+    path
+  }
+
+}