Find minimum and maximum values in a list of objects in Kotlin

Given a list of objects, find minimum and maximum values in a list of objects in Kotlin.

1. Using `minWith()` & `maxWith()` function

The recommended solution is to find the minimum value in the list of objects is with the minWith() function that accepts a Comparator to compare objects based on a field value. Similarly, to find the maximum value in the list, you can use the maxWith() function.

data class Emp(var name: String, var age: Int)

fun main() {

val list = listOf(Emp("Vicki", 15), Emp("Mike", 10), Emp("Frank", 12))

// get an employee with a minimum age

val minAgeEmp = list.minWith(Comparator.comparingInt {it.age })

println("Minimum : $minAgeEmp")

// get an employee with a maximum age

val maxAgeEmp = list.maxWith(Comparator.comparingInt { it.age })

println("Maximum : $maxAgeEmp")

}

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Output:

Minimum : Emp(name=Mike, age=10)
Maximum : Emp(name=Vicki, age=15)

2. Using Reduce Operation

Alternatively, you can perform the reduction operation on the list objects using the reduce() function that takes the comparison object.

data class Emp(var name: String, var age: Int)

internal object Compare {

fun min(a: Emp, b: Emp): Emp {

return if (a.age < b.age) a else b

}

fun max(a: Emp, b: Emp): Emp {

return if (a.age > b.age) a else b

}

fun main() {

val list = listOf(Emp("Vicki", 15), Emp("Mike", 10), Emp("Frank", 12))

// get an employee with a minimum age

val minAgeEmp = list.reduce(Compare::min)

println("Minimum : $minAgeEmp")

// get an employee with a maximum age

val maxAgeEmp = list.reduce(Compare::max)

println("Maximum : $maxAgeEmp")

}

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Output:

Minimum : Emp(name=Mike, age=10)
Maximum : Emp(name=Vicki, age=15)

That’s all about finding the minimum and maximum values in a list of objects in Kotlin.

Find minimum and maximum values in a list of objects in Kotlin

1. Using minWith() & maxWith() function

2. Using Reduce Operation

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1. Using `minWith()` & `maxWith()` function