I'm starting to learn Kotlin. I'm pretty sure a large majority of all Android devs are also doing this right now. There are plenty of blog posts, videos, podcasts, talks etc. etc. being produced. Rather than doing another learn X or whatever about Kotlin blog post, my intention is to post things here that I've found particularly interesting or useful. Therefore, what you're reading is incomplete, may never be completed and might make no f***ing sense. But I'm keen to get things down so that I have something to come back to. And maybe you might find it interesting as well. Or not. It doesn't matter, this isn't for you, this is for future Mike 👋 (Remember to fry the pillow)

Beginner resources

Blog posts

Advanced Resources

Blog posts


Language Features


What's the difference between a field in Java and a property in Kotlin? There's a lot more to a property in Kotlin, the default includes accessors and you can even do propert delegation. This article explains it all well.


Usually in Java I would new up an ArrayList and then add everything I needed to it, line after line after line...No more! While you can do it that way in Kotlin, you can also do this:

val strings = arrayListOf("Android", "Snacks", "Rocks)

This will give me an ArrayList of String without the need for all those extra lines. There's also listOf, mutableListOf, listOfNotNull and emptyList.


Singleton with single argument

If you need to create a Singleton with an argument then you need to check out this blog post by Christoper Beyls which shows how to implement a double locking mechanism in Kotlin.

Sealed Classes

This is a great example (and explanation) on how they can be used to handle success and errors in an RxJava stream.



Properties in Kotlin can be inlined! this will help produce more optimal bytecode.

Custom Property Delegates





Run, with, let, also and apply