- Scala Collections Tutorial
- Scala Collections - Home
- Scala Collections - Overview
- Scala Collections - Environment Setup
- Scala Collections - Arrays
- Scala Collections - Array
- Scala Collections - Multi-Dimensional Array
- Scala Collections - Array using Range
- Scala Collections - ArrayBuffer
- Scala Collections - Lists
- Scala Collections - List
- Scala Collections - ListBuffer
- Scala Collections - ListSet
- Scala Collections - Vector
- Scala Collections - Sets
- Scala Collections - Set
- Scala Collections - BitSet
- Scala Collections - HashSet
- Scala Collections - TreeSet
- Scala Collections - Maps
- Scala Collections - Map
- Scala Collections - HashMap
- Scala Collections - ListMap
- Scala Collections - Miscellaneous
- Scala Collections - Iterator
- Scala Collections - Option
- Scala Collections - Queue
- Scala Collections - Tuple
- Scala Collections - Seq
- Scala Collections - Stack
- Scala Collections - Stream
- Scala Collections Combinator methods
- Scala Collections - drop
- Scala Collections - dropWhile
- Scala Collections - filter
- Scala Collections - find
- Scala Collections - flatMap
- Scala Collections - flatten
- Scala Collections - fold
- Scala Collections - foldLeft
- Scala Collections - foldRight
- Scala Collections - map
- Scala Collections - partition
- Scala Collections - reduce
- Scala Collections - scan
- Scala Collections - zip
- Scala Collections Useful Resources
- Scala Collections - Quick Guide
- Scala Collections - Useful Resources
- Scala Collections - Discussion
Scala Collections - Fold Method
fold() method is a member of TraversableOnce trait, it is used to collapse elements of collections.
Syntax
The following is the syntax of fold method.
def fold[A1 >: A](z: A1)(op: (A1, A1) ? A1): A1
Here, fold method takes associative binary operator function as a parameter. This method returns the result as value. It considers first input as initial value and second input as a function (which takes accumulated value and current item as input).
Usage
Below is an example program of showing how to use fold method −
Example
object Demo {
def main(args: Array[String]) = {
val list = List(1, 2, 3 ,4)
//apply operation to get sum of all elements of the list
val result = list.fold(0)(_ + _)
//print result
println(result)
}
}
Here we've passed 0 as initial value to fold function and then all values are added. Save the above program in Demo.scala. The following commands are used to compile and execute this program.
Command
\>scalac Demo.scala \>scala Demo
Output
10
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