Book Image

Programming Kotlin

Book Image

Programming Kotlin

Overview of this book

Quickly learn the fundamentals of the Kotlin language and see it in action on the web. Easy to follow and covering the full set of programming features, this book will get you fluent in Kotlin for Android.
Table of Contents (20 chapters)
Programming Kotlin
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Customer Feedback
Preface

Generic functions


Have you ever written a function for one type and then you had to write it again for another type? Perhaps you wrote a function that worked for strings and then had to write the same function again for integers.

To avoid such a case, functions can be generic in the types they use. This allows a function to be written that can work with any type, rather than a specific type only. To do this, we define the type parameters in the function signature:

    fun <T> printRepeated(t: T, k: Int): Unit { 
      for (x in 0..k) { 
        println(t) 
      } 
    } 

In this example, we print the t element k number of times. You might be thinking that we could have defined this function using Any and it would still work, since println is defined to accept Any itself. That's correct! However, what you can't do with Any is ensure that multiple parameters are of the same type and that return values are the same as the input type. Let's say we want a function...