Kotlin gives the programmer the ability to add more functionality to the existing classes, without inheriting them.
This is achieved through a feature known as extensions.
When a function is added to an existing class it is known as Extension Function.
To add an extension function to a class, define a new function appended to the class name.
For Example :
fun main() {
val list = mutableListOf(1,2,3,4)
list.swap(0,2)
print(list)
}
fun MutableList<Int>.swap(index1: Int, index2: Int) {
val tmp = this[index1] // 'this' corresponds to the list
this[index1] = this[index2]
this[index2] = tmp
}
Output : [3,2,1,4]
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