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[SCALA-729] - Convert Java List to Scala Seq #1361

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May 29, 2024
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Original file line number Diff line number Diff line change
@@ -0,0 +1,45 @@
package com.baeldung.scala.javatoscalaseq

import java.util
import scala.jdk.javaapi.CollectionConverters
import scala.collection.JavaConverters

object ConvertJavaAListToScalaSeq {

private def takeSeq(seq: Seq[String]): String = {
seq.mkString
}

def in212(list: util.List[String]): String = {
val scalaSeq: Seq[String] =
JavaConverters.collectionAsScalaIterable(list).toSeq
takeSeq(scalaSeq)
}

def in213(list: util.List[String]): String = {
val scalaSeq: Seq[String] = CollectionConverters.asScala(list).toSeq
takeSeq(scalaSeq)
}

def convertToList212(list: util.List[String]): String = {
val scalaList: List[String] =
JavaConverters.collectionAsScalaIterable(list).toList
val scalaSet: Set[String] =
JavaConverters.collectionAsScalaIterable(list).toSet
val scalaIndexedSeq: IndexedSeq[String] =
JavaConverters.collectionAsScalaIterable(list).toIndexedSeq
val scalaVector: Vector[String] =
JavaConverters.collectionAsScalaIterable(list).toVector
takeSeq(scalaList)
}

def convertToList213(list: util.List[String]): String = {
val scalaList: List[String] = CollectionConverters.asScala(list).toList
val scalaSet: Set[String] = CollectionConverters.asScala(list).toSet
val scalaIndexedSeq: IndexedSeq[String] =
CollectionConverters.asScala(list).toIndexedSeq
val scalaVector: Vector[String] =
CollectionConverters.asScala(list).toVector
takeSeq(scalaList)
}
}
Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
package com.baeldung.scala.javatoscalaseq

import java.util
import org.scalatest.flatspec.AnyFlatSpec
import org.scalatest.matchers.should.Matchers

class ConvertJavaAListToScalaSeqUnitTest extends AnyFlatSpec with Matchers {
val list: util.List[String] = util.ArrayList[String]()
list.add("hello")
list.add(" world")

"212" should "return String" in {
ConvertJavaAListToScalaSeq.in212(list) shouldBe "hello world"
}

"213" should "return String" in {
ConvertJavaAListToScalaSeq.in213(list) shouldBe "hello world"
}

"convertToList212" should "return String" in {
ConvertJavaAListToScalaSeq.convertToList212(list) shouldBe "hello world"
}

"convertToList213" should "return String" in {
ConvertJavaAListToScalaSeq.convertToList213(list) shouldBe "hello world"
}
}