Java’cılar Için Scala – 2 [Collections]

By Cem Dırman Last updated Dec 14, 2021

Bu yazıda Scala’daki collection yapılarını inceleyeceğiz.

Bir önceki yazıyı okumadıysanız aşağıdaki linkten ulaşabilirsiniz.

Array

Java’da bir array tanımı için köşeli parantezler(‘[]’), tip belirtiyor ve de boyut vermemiz gerekiyordu. Scala’da ise direkt olarak böyle bir tipimiz mevcut. Bu sayede ise çeşitli fonksiyonlara da ulaşabilir oluyoruz. Tabii ki Java’da da Arrays class’ı mevcut dolaylı da olsa Scala’da var olan methodları gerçekleştirebiliriz.



object Collections {

  def main(args: Array[String]): Unit ={

    val nameList: Array[String] = new Array[String](3)

    val ageList = Array(5,3,8,7,1,9,23)

    nameList(0) = "biilisim.io"
    nameList(1) = "cem"
    nameList(2) = "nehir"

    for (i <- 0 until  nameList.length){
      println(nameList(i))
    }

    ageList.map(age => println(age))

    ageList.update(0,13) //replace
    val minNumber = ageList.min
    val maxNumber = ageList.max
    val head = ageList.head
    val last = ageList.last
    println(minNumber + " - " + maxNumber + " - " + head + " - " + last) // 1 - 23 - 13 - 23

    val newAgeList: Array[Int] = ageList.drop(3) // listenin başından 3 elaman siler 
    newAgeList.map(age => println(age))


    val numbers = (1 to 10).toArray // until de kullanılabilir.
    numbers.map(number => println(number))

  }

}

object Collections {

def main(args: Array[String]): Unit ={

val nameList: Array[String] = new Array[String](3)

val ageList = Array(5,3,8,7,1,9,23)

nameList(0) = "biilisim.io"

nameList(1) = "cem"

nameList(2) = "nehir"

for (i <- 0 until nameList.length){

println(nameList(i))

}

ageList.map(age => println(age))

ageList.update(0,13) //replace

val minNumber = ageList.min

val maxNumber = ageList.max

val head = ageList.head

val last = ageList.last

println(minNumber + " - " + maxNumber + " - " + head + " - " + last) // 1 - 23 - 13 - 23

val newAgeList: Array[Int] = ageList.drop(3) // listenin başından 3 elaman siler

newAgeList.map(age => println(age))

val numbers = (1 to 10).toArray // until de kullanılabilir.

numbers.map(number => println(number))

}

Collections

1. List

List’ler immutable yani değiştirilemezler eğer List’e ekleme yapmak istiyorsanız ArrayBuffer ve ya ListBuffer öneriliyor. Bu konu stackoverflow‘da tartışılmış incelemek isterseniz bakabilirsiniz.



    val cities: List[String] = List("İstanbul","Sinop","Bursa","Konya")
    cities.foreach(city => println(city))

    var list: ListBuffer[Int] = ListBuffer()
    list += 4
    list += 7

    var fruits = new ListBuffer[String]()
    fruits += "mandalina"
    fruits += "portakal"
    fruits.foreach(fruit => println(fruit))

    val list1: List[String] = Nil

    val istanbul = cities.head
    var tailCity = cities.tail
    val isEmpty: Boolean = cities.isEmpty

val cities: List[String] = List("İstanbul","Sinop","Bursa","Konya")

cities.foreach(city => println(city))

var list: ListBuffer[Int] = ListBuffer()

list += 4

list += 7

var fruits = new ListBuffer[String]()

fruits += "mandalina"

fruits += "portakal"

fruits.foreach(fruit => println(fruit))

val list1: List[String] = Nil

val istanbul = cities.head

var tailCity = cities.tail

val isEmpty: Boolean = cities.isEmpty

2. Set

Hem mutable hem de immutable Set oluşturulabilir.



    val citySet: Set[String] = Set("İzmir","Muğla","Erzurum")
    citySet += "Van" // compiler error. Çünkü immutable 

    var superLig: Set[String] = Set()
    superLig += "fenerbahçe"
    superLig += "galatasaray"
    superLig += "beşiktaş"
    superLig += "trabzonspor"

    var ptt: Set[String] = Set("ankaragücü")
    ptt += "ordu spor"
    ptt += "giresun spor"
    ptt += "giresun spor"

    val allTeams: Set[String] = superLig ++ ptt

    allTeams.foreach(team => println(team))

val citySet: Set[String] = Set("İzmir","Muğla","Erzurum")

citySet += "Van" // compiler error. Çünkü immutable

var superLig: Set[String] = Set()

superLig += "fenerbahçe"

superLig += "galatasaray"

superLig += "beşiktaş"

superLig += "trabzonspor"

var ptt: Set[String] = Set("ankaragücü")

ptt += "ordu spor"

ptt += "giresun spor"

val allTeams: Set[String] = superLig ++ ptt

allTeams.foreach(team => println(team))

3. Map

Hem mutable hem de immutable Map oluşturulabilir.



    val immutableMap = Map(1 -> "cem", 2 -> "emir")
    //immutableMap += 3 -> "necip" // compiler error
    val mutableMap = collection.mutable.Map(1 -> "serra", 2 -> "nehir")
    mutableMap += 3 -> "necip"
    mutableMap += 4 -> "enes"

    var isMapEmpty: Boolean = immutableMap.isEmpty
    var value: Option[String] = immutableMap.get(1)
    if (value.nonEmpty){
      println(value.get)
      println("map size:" + immutableMap.size)
    }

    mutableMap.foreach(key => println("key: " + key._1 + ", value: " + key._2))

    mutableMap.remove(4)

    mutableMap.foreach(key => println("key: " + key._1 + ", value: " + key._2)

val immutableMap = Map(1 -> "cem", 2 -> "emir")

//immutableMap += 3 -> "necip" // compiler error

val mutableMap = collection.mutable.Map(1 -> "serra", 2 -> "nehir")

mutableMap += 3 -> "necip"

mutableMap += 4 -> "enes"

var isMapEmpty: Boolean = immutableMap.isEmpty

var value: Option[String] = immutableMap.get(1)

if (value.nonEmpty){

println(value.get)

println("map size:" + immutableMap.size)

}

mutableMap.foreach(key => println("key: " + key._1 + ", value: " + key._2))

mutableMap.remove(4)

mutableMap.foreach(key => println("key: " + key._1 + ", value: " + key._2)

4. Tuples

Farklı tipteki verileri saklayabileceğiniz bir yapıdır. Bazı diller de bu yapıya yer vermektedir. Fakat Java’da direkt olarak bir karşılığı yok.



    val friendTuple = ("Haluk", 28,"ios developer",8.8, true)
    val (name, age, job,score, isPlayer) = ("Ömer", 27,"java developer",9.8, false)
    val (name1, age1, job1, score1, isPlayer1) = ("Halil", 27,"android developer",14.8, false)

    println(friendTuple._1 + " - " + friendTuple._2)
    println(name + " - " + score + " - " + job)

val friendTuple = ("Haluk", 28,"ios developer",8.8, true)

val (name, age, job,score, isPlayer) = ("Ömer", 27,"java developer",9.8, false)

val (name1, age1, job1, score1, isPlayer1) = ("Halil", 27,"android developer",14.8, false)

println(friendTuple._1 + " - " + friendTuple._2)

println(name + " - " + score + " - " + job)

Bütün kodlar;



import java.util
import scala.::
import scala.collection.mutable
import scala.collection.mutable.ListBuffer

object Collections {

  def main(args: Array[String]): Unit ={

    val nameList: Array[String] = new Array[String](3)

    val ageList = Array(5,3,8,7,1,9,23)

    nameList(0) = "biilisim.io"
    nameList(1) = "cem"
    nameList(2) = "nehir"

    for (i &lt;- 0 until  nameList.length){
      println(nameList(i))
    }

    ageList.map(age =&gt; println(age))

    ageList.update(0,13) //replace
    val minNumber = ageList.min
    val maxNumber = ageList.max
    val head = ageList.head
    val last = ageList.last
    println(minNumber + " - " + maxNumber + " - " + head + " - " + last) // 1 - 23 - 13 - 23

    val newAgeList: Array[Int] = ageList.drop(3) // listenin başından 3 elaman siler
    newAgeList.map(age =&gt; println(age))

    println("---")

    val numbers = (1 to 10).toArray // until de kullanılabilir.
    numbers.map(number =&gt; println(number))

    println("--Collections--")

    val cities: List[String] = List("İstanbul","Sinop","Bursa","Konya")
    cities.foreach(city =&gt; println(city))

    var list: ListBuffer[Int] = ListBuffer()
    list += 4
    list += 7

    var fruits = new ListBuffer[String]()
    fruits += "mandalina"
    fruits += "portakal"
    fruits.foreach(fruit =&gt; println(fruit))

    val list1: List[String] = Nil

    val istanbul = cities.head
    var tailCity = cities.tail
    val isEmpty: Boolean = cities.isEmpty

    val citySet: Set[String] = Set("İzmir","Muğla","Erzurum")
    //citySet += "Van" // compiler error. Çünkü immutable

    var superLig: Set[String] = Set()
    superLig += "fenerbahçe"
    superLig += "galatasaray"
    superLig += "beşiktaş"
    superLig += "trabzonspor"

    var ptt: Set[String] = Set("ankaragücü")
    ptt += "ordu spor"
    ptt += "giresun spor"
    ptt += "giresun spor"

    val allTeams: Set[String] = superLig ++ ptt

    allTeams.foreach(team =&gt; println(team))

    println("--MAP--")

    val immutableMap = Map(1 -&gt; "cem", 2 -&gt; "emir")
    //immutableMap += 3 -&gt; "necip" // compiler error
    val mutableMap = collection.mutable.Map(1 -&gt; "serra", 2 -&gt; "nehir")
    mutableMap += 3 -&gt; "necip"
    mutableMap += 4 -&gt; "enes"

    var isMapEmpty: Boolean = immutableMap.isEmpty
    var value: Option[String] = immutableMap.get(1)
    if (value.nonEmpty){
      println(value.get)
      println("map size:" + immutableMap.size)
    }

    mutableMap.foreach(key =&gt; println("key: " + key._1 + ", value: " + key._2))

    mutableMap.remove(4)

    mutableMap.foreach(key =&gt; println("key: " + key._1 + ", value: " + key._2))


    println("--TUPLES--")

    val friendTuple = ("Haluk", 28,"ios developer",8.8, true)
    val (name, age, job,score, isPlayer) = ("Ömer", 27,"java developer",9.8, false)
    val (name1, age1, job1, score1, isPlayer1) = ("Halil", 27,"android developer",14.8, false)

    println(friendTuple._1 + " - " + friendTuple._2)
    println(name + " - " + score + " - " + job)


  }

}

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import java.util

import scala.::

import scala.collection.mutable

import scala.collection.mutable.ListBuffer

object Collections {

def main(args: Array[String]): Unit ={

val nameList: Array[String] = new Array[String](3)

val ageList = Array(5,3,8,7,1,9,23)

nameList(0) = "biilisim.io"

nameList(1) = "cem"

nameList(2) = "nehir"

for (i <- 0 until nameList.length){

println(nameList(i))

}

ageList.map(age => println(age))

ageList.update(0,13) //replace

val minNumber = ageList.min

val maxNumber = ageList.max

val head = ageList.head

val last = ageList.last

println(minNumber + " - " + maxNumber + " - " + head + " - " + last) // 1 - 23 - 13 - 23

val newAgeList: Array[Int] = ageList.drop(3) // listenin başından 3 elaman siler

newAgeList.map(age => println(age))

println("---")

val numbers = (1 to 10).toArray // until de kullanılabilir.

numbers.map(number => println(number))

println("--Collections--")

val cities: List[String] = List("İstanbul","Sinop","Bursa","Konya")

cities.foreach(city => println(city))

var list: ListBuffer[Int] = ListBuffer()

list += 4

list += 7

var fruits = new ListBuffer[String]()

fruits += "mandalina"

fruits += "portakal"

fruits.foreach(fruit => println(fruit))

val list1: List[String] = Nil

val istanbul = cities.head

var tailCity = cities.tail

val isEmpty: Boolean = cities.isEmpty

val citySet: Set[String] = Set("İzmir","Muğla","Erzurum")

//citySet += "Van" // compiler error. Çünkü immutable

var superLig: Set[String] = Set()

superLig += "fenerbahçe"

superLig += "galatasaray"

superLig += "beşiktaş"

superLig += "trabzonspor"

var ptt: Set[String] = Set("ankaragücü")

ptt += "ordu spor"

ptt += "giresun spor"

val allTeams: Set[String] = superLig ++ ptt

allTeams.foreach(team => println(team))

println("--MAP--")

val immutableMap = Map(1 -> "cem", 2 -> "emir")

//immutableMap += 3 -> "necip" // compiler error

val mutableMap = collection.mutable.Map(1 -> "serra", 2 -> "nehir")

mutableMap += 3 -> "necip"

mutableMap += 4 -> "enes"

var isMapEmpty: Boolean = immutableMap.isEmpty

var value: Option[String] = immutableMap.get(1)

if (value.nonEmpty){

println(value.get)

println("map size:" + immutableMap.size)

}

mutableMap.foreach(key => println("key: " + key._1 + ", value: " + key._2))

mutableMap.remove(4)

mutableMap.foreach(key => println("key: " + key._1 + ", value: " + key._2))

println("--TUPLES--")

val friendTuple = ("Haluk", 28,"ios developer",8.8, true)

val (name, age, job,score, isPlayer) = ("Ömer", 27,"java developer",9.8, false)

val (name1, age1, job1, score1, isPlayer1) = ("Halil", 27,"android developer",14.8, false)

println(friendTuple._1 + " - " + friendTuple._2)

println(name + " - " + score + " - " + job)

}

https://docs.scala-lang.org/overviews/collections/overview.html

Faydalı olması dileğiyle.