This tutorial assumes that all you know is Java, but you want to learn Kotlin.

Please note that the resources are in the wiki page.

A few things that are worth watching to know more about Kotlin.

• By me: Odd things to look out for when converting code to Kotlin

• By me: Code clean-up with Kotlin

• By me (newer article!): An opinionated guide on how to make your Kotlin code fun to read and joy to work with

• Android KTX source code: Github snapshot or AOSP (actively developed)

• Jake Wharton: Instrumentation Testing Robots

• How to Kotlin - from the Lead Kotlin Language Designer (Google I/O '18)

• Droidcon NYC 2018: Advanced Kotlin

• Google I/O 2017 - Jake Wharton / Christina Lee: Life is Great and Everything will be OK: Kotlin is here

https://www.reddit.com/r/androiddev/comments/77sl1c/devs_who_review_kotlin_regularly_what_are_things/dorsk3i/

• inverted argument order, no semi-colons, void vs Unit, Object vs Any?, fun

• interfaces with val, var and fun

• constructors, inheritance

• lateinit vars

• enum class

• annotation class

• final by default vs open

• for loops (in ranges, until)

• object for singleton

• statics via companion object, const val

• visibility in Kotlin (public by default, private, protected, internal)

• static nested class in Java vs inner class in Kotlin

• backticks for reserved keywords (Mockito.when, $) and import aliases

• is instead of instanceof, as and as? for casting

• creating anonymous implementations for classes/interfaces

• there is no condition ? true : false ternary operator

• arrayOf and arrayOfNulls and listOf and mutableListOf and linkedMapOf

• array literals in annotations (for vararg parameters)

• operator conventions (get() vs [], .equals() vs ==)

• there are no checked exceptions, try-with-resources as .use {}

• @Volatile and synchronized

• multiple generic bounds

• typed nullability, and null-safety operators (?., ?:)

• smart casting (and mutable vars gotcha)

• lateinit vars

• properties, backing fields

• string interpolation and """multiline escaped ${strings}"""

• data classes

• when keyword (and complex conditions, such as ranges)

• control statement as expression (assignment of when, return, ...)

• named arguments, default arguments

• vararg and the * spread operator

• interfaces and default implementation

• generics (<T: Blah>, in/out, and star projection <*>)

• lambda types, trailing lambdas

• method reference

• typealias

• lambdas with receivers

• extension functions, extension properties

• standard library functions - scoping functions: apply, let, also, run, with

• standard library functions - more utility functions: takeIf, takeUnless

• tailrec keyword

• inline functions (crossinline, noinline)

• *a glance at the Collections API (see API here)

• inline fun <reified T>

• sealed classes

• infix keyword

• tuples (to) and destructuring

• *extension operators (componentN)

• *property delegates (and built-in ones: lazy, observable/vetoable, by map for configurations via Map<String, Any?>)

• delegation by class

• *JVM annotations: @JvmOverloads, @JvmField, @JvmSuppressWildcards, @get: and @set: and @field:

• synthetic view accessors with kotlin android extensions (deprecated)

• @Parcelize data class with experimental kotlin android extensions

• Coroutines, coroutines on Android, suspend fun

• Channels: LinkedListChannel, BroadcastChannel

• @DslMarker

• multi-platform things: expect and actual

• contracts

Copyright 2018-2020 Gabor Varadi
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
   https://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
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