Each data class object has a component for each property like component1, component2, etc.. I was wondering if there is any way in Kotlin to iterate over each component of a class. Say I have class:
data class User(age:Int, name:String)
Could I do something like:
for(component in aUserObject){ //do some stuff with age or name }
?
The for loop is used to iterate over any Kotlin object which can be iterated. We can iterate over an array, collection, string, range, or anything which can be iterated with the help of a for loop.
We can use the listIterator() method for iterating through lists in both forward and backward directions.
In Kotlin, Reflection is a combination of language and library capabilities that allow you to introspect a program while it's running. Kotlin reflection is used at runtime to utilize a class and its members, such as properties, methods, and constructors.
First of all, the componentN
properties are available only on data classes, not on every object.
There is no API specifically for iterating over the components, but you can use the Kotlin reflection to iterate over properties of any class:
class User(val age: Int, val name: String) fun main(args: Array<String>) { val user = User(25, "Bob") for (prop in User::class.memberProperties) { println("${prop.name} = ${prop.get(user)}") } }
also, you can use Properties Delegation with built-in delegate 'by map'. it's very useful for some simple stat classes.
class DbUsingStat { private val map = mutableMapOf( "removed" to 0, "updated" to 0, "skipped" to 0 ) var removed by map var updated by map var skipped by map fun asMap() : Map<String, Int> = map.toMap() } ... ... val someStatistic = DbUsingStat().apply { skipped = 5 removed = 10 updated = 1505 } for((k, v) in someStatistic.asMap()) println("$k: $v")
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