The sumOf method of List applies the provided selector function on each element and returns the sum of the values returned by the selector function for each element of the List.
@JvmName("sumOfInt") inline fun <T> Iterable<T>.sumOf(
selector: (T) -> Int
): Int
Note: This method has multiple syntaxes for different data types. Please click here to learn more.
This method takes an inline function (selector) as an argument.
This method returns the sum of all values produced by the selector function applied on each element.
The code below demonstrates how to use the sumOf method in Kotlin.
fun main() {//create a list with int elements elementsval list:List<Int> = listOf(1,2,3)println("\nlist : ${list}")var sum = list.sumOf{it*2}println("Sum of all elements after multiplyying each element by 2 : ${sum}")sum = list.sumOf{it * it}println("Sum of all elements after square each element : ${sum}")}
Line 3: We create a List with the name list using the listOf method. The list will have three elements 1,2,3.
Line 6: We use the sumOf method with a selector function. The selector function multiplies the element by 2 and returns it. In our case, the selector function returns:
1, 2 is returned.2, 4 is returned.3, 6 is returned.The above values are summed and returned as a result. The result is 12.
Line 9: We use the sumOf method with a selector function. The selector function squares the element and returns it. In our case, the selector function returns:
1, 1 is returned.2, 4 is returned.3, 9 is returned.The above values are summed and returned as a result. The result is 14.