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### Scala – Collections

• date 5th October, 2020 |
• by Prwatech |
• 0 Comments

Scala consists of rich set of collection library. Collections consist of list of items. Those items can be sequenced in a way like Array, List, Tuple, Option, Map, iterator, sets etc.

1) Array

a)

` `
`val n = new Array[Int](5) scala> val st = new Array[String](5) scala> val st = Array("Big","Data","s","s","t","u","u","w","w") valst1=Array("Hello","Prwatech","p","s","t","u","v","w","x","y","z","z","b","c","d","e")`
` `

b)

` `

2) List

a)

``scala> val lst = List(5,6)``
``scala> lst.head``
``scala> lst.tail``

#Adding new elements using “::” from given head and tail

``scala> 4 : : lst``

b)

``````scala> var lst = List(5,6,”d”,”e”,”1″)

scala> lst.head

scala> lst.tail

scala> “e”::List(“5″,”1”)

scala> “4”::lst``````

3) Tuples

a)

``````scala> val a = (1,3,”Prwatech”,1.5)

scala> a._2

scala> a._3

scala> a._4``````

b)

``````scala> val x = (“ab”,3,”Prwa”,1.5,”i”)

scala> x._1

scala> x._4

scala> x._5``````

4) Map

a)

``````scala> val mapping = Map(“Tom” -> “Hardy”,”Christian” -> “Bale”)

scala>  val mapping = scala.collection.mutable.Map(“Leonardo” -> “D”,”Brad” -> “B”)

scala> val x = mapping(“Tom”)``````

Accessing Map

``````scala> val mapping = Map(“Tom” -> “Hardy”,”Christian” -> “Bale”)

scala>  val mapping = scala.collection.mutable.Map(“Leonardo” -> “D”,”Brad” -> “B”)

scala> val x = mapping(“Leonardo”)``````

Iterating Map elements

``scala> for((d,b) <- mapping) yield(b,d)``

b)

``````Scala> val mapping = Map(“Prwa” -> “utkarsh”,”Vinay” -> “Verma”)

Scala> val mapping = scala.collection.mutable.Map(“Vishal” -> “K”,”Vijay” -> “v”)

Scala> val x = mapping(“Prwa”)``````

Accessing Map elements

``````Scala> val mapping = Map(“Prwa” -> “utkarsh”,”Vinay” -> “Verma”)

Scala>  val mapping = scala.collection.mutable.Map(“Vishal” -> “K”,”Vijay” -> “v”)

Scala> val x = mapping(“Vishal”)``````

Iterating Map elements

`` Scala> for((k,v) <- mapping) yield(v,k)``

5) ArrayBuffer

a)

``````scala> import scala.collection.mutable.ArrayBuffer

scala> val x = ArrayBuffer[Int]()

scala> x+=1

scala> print(x++=Array(3,4,5))

scala> print(x++=Array(6))

scala> print(x+=(7))``````

b)

``````scala> import scala.collection.mutable.ArrayBuffer

scala> val x = ArrayBuffer[String]()

scala> x+=”a”

scala> print(x++=Array(“b”,”c”,”d”))

scala> print(x++=Array(“e”))

scala> print(x+=(“f”))``````

6) Set

A Scala Set is a type of collection that doesn't accept duplicates

a)

``````scala> var s=Set(1,2,3,3,2,5)

scala> var s:Set[Int]=Set(1,2,3,3,5)

scala> s.head

scala> s.tail

scala> s.isEmpty
val res3: Boolean = false

scala> var s1=Set(7,9,8,9)

//concatenating two sets s and s1

scala> s++s1

//find max no from s and s1 set

scala> s.max

scala> s1.max

//find min no from sets s1 and s

scala> s1.min

scala> s.min
``````

b)

``````scala> val a=Set(9,9,3,3,2,”a”,7,”b”)

scala> a.head

scala> a.tail

``````