Scala - Multiple ways to iterate over a Map in Scala

Category : Scala | Sub Category : Scala Programs | By Prasad Bonam Last updated: 2023-10-01 02:04:43 Viewed : 562

Iterating over a Map in Scala can be done in various ways, depending on your specific needs. Here are multiple ways to iterate over a Map in Scala with output:

Assuming you have a Map like this:

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val myMap = Map("Alice" -> 25, "Bob" -> 30, "Charlie" -> 22)

1. Using a For-Each Loop:

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for ((key, value) <- myMap) {
  println(s"Key: $key, Value: $value")
}

2. Using the foreach Method:

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myMap.foreach { case (key, value) =>
  println(s"Key: $key, Value: $value")
}

3. Using map and foreach (functional approach):

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myMap.map { case (key, value) =>
  println(s"Key: $key, Value: $value")
}

4. Using a While Loop and an Iterator:

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val iterator = myMap.iterator
while (iterator.hasNext) {
  val (key, value) = iterator.next()
  println(s"Key: $key, Value: $value")
}

5. Using a for comprehension (functional approach):

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for {
  (key, value) <- myMap
} println(s"Key: $key, Value: $value")

6. Using a Tail-Recursive Function:

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import scala.annotation.tailrec

@tailrec
def printMap(map: Map[String, Int]): Unit = {
  if (map.nonEmpty) {
    val ((key, value), remainingMap) = (map.head, map.tail)
    println(s"Key: $key, Value: $value")
    printMap(remainingMap)
  }
}

printMap(myMap)

7. Using keys and values methods:

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for (key <- myMap.keys) {
  val value = myMap(key)
  println(s"Key: $key, Value: $value")
}

8. Using mapKeys and mapValues methods (functional approach):

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myMap.map { case (key, value) =>
  val transformedKey = s"Transformed $key"
  val transformedValue = value * 2
  println(s"Key: $transformedKey, Value: $transformedValue")
}

These are various ways to iterate over a Map in Scala. You can choose the one that best suits your coding style and the specific requirements of your application.