My notes on scala.lists :
– scala.list is different from java.util.List
– scala.list is ‘immutable sequence of objects’
– scala list doesn’t support append operation
Some Scala list operators and methods:
- ::: – for list concatenation
scala > val oneTwo = List(1, 2)
scala > val threeFour = List(3, 4)
scala > val oneTwoThreeFour = oneTwo ::: threeFour
- :: – cons operator – prepends a new element to the begging of an existing list
scala > val twoThree = List(2,3)
scala > valOneTwoThree = 1 :: twoThree - cons operator is method of right hand operand
scala > val oneTwoThree = 1 :: 2 :: 3 :: Nil - index operation : thrill(2)
scala > val thrill = “Will” :: “fill” :: “until” :: Nil
scala > thrill(2)
- create empty Scala’s list :
scala > List()
scala > Nil - create a new List[String]
scala > List(“Cool”, “tools”, “rule”) - counts the number of list elements
scala > val thrill = “Will” :: “fill” :: “until” :: Nil
scala > thrill.count(s=>s.length == 4)
Reference :