Kotlin Archives - Page 2 of 3 - Kotlin Expertise Blog

29Jun 2018 by Jovche Mitrejcevski 3 Comments

Android KTX – Android development with Kotlin

Android, Kotlin, Software Development, Teaching, Tutorial

Introduction Android KTX is an open source library or set of functionalities designed to make the Android development with Kotlin even more pleasant. You can find its website here. The abbreviation KTX stands for Kotlin Extensions, so this library is basically a set of extension functions, extension properties and other top-level functions. In this article, we take a look at what's inside this library and how we can take advantage of it. This library's goal is not to add new features to the existing Android APIs, but rather make those APIs easier to use by leveraging the features of the Kotlin language. Structure of Android KTX A very important thing to note at the beginning is that Android KTX provides functionalities which would be added to many individual projects by…

24Jun 2018 by s1m0nw1 2 Comments

Kotlin Nullability Features

Functional Programming, Java, Kotlin, Software Development, Teaching, Tutorial

Null-Safe Programming - The Kotlin Way Disclaimer: This ktor article was originally published in the Dzone Java Guide 2018, which can be downloaded here. In this article, we will review the problems that may be caused by null pointers and how to avoid them in Java. After that, the article demonstrates how Kotlin nullability features work and how they improve your code. As Java developers, we're very accustomed to NullPointerExceptions (NPE) that are thrown at the runtime of an application. This almost always happens unintentionally in consequence of a bug, which is based on unrecognized references to null. The null reference is often used to indicate absent values, which isn't obvious to the programmer in many cases. Although Java relies on strong static typing, it doesn't let you distinguish between…

12May 2018 by s1m0nw1 4 Comments

Run Kotlin Scripts (kts) from regular Kotlin Programs

Gradle, Java, Kotlin, Software Development

Run Kotlin Scripts from Kotlin Programs This article presents a way to run Kotlin scripts from Kotlin programs in order to leverage the power of DSLs. Kotlin can be used as a scripting language. Simply write top-level executable code inside a file with .kts extension and run it with the kotlinc as described in the documentation. That's also the format of Gradle build files that are used in combination with the Gradle Kotlin DSL like this gradle.build.kts. Gradle shows a fantastic example of a domain specific language that can be written standalone in .kts files to be read by the gradle tool later on. When we try to find a way to do the same with custom DSLs (Tutorial can be found here), we first need to know how to…

14Apr 2018 by s1m0nw1 6 Comments

Why you should start contributing to StackOverflow

Kotlin, Software Development, Teaching, Tutorial

A little History A few years back, when I started getting into programming, I googled a lot of the problems I was facing during the day and mostly found my answers on StackOverflow. The place that every programmer is kind of dependent on. I still face problems and I still find my answers on StackOverflow. Something has changed, though. I don't only consume content on the website but also contribute to it. Until May 2017, I didn't even have an account on StackOverflow. At this time, I was getting interested in knowing how it's like to answer questions instead of just reading them. I enjoyed helping others to solve their Kotlin-related problems ever since I started learning the Kotlin programming language. This was my initial motivation for creating an account and…

16Mar 2018 by s1m0nw1 7 Comments

Coping with Kotlin’s Scope Functions: let, run, also, apply, with

Functional Programming, Kotlin, Software Development

Coping with Kotlin's Scope Functions Functions in Kotlin are very important and it's much fun() to use them. One special collection of relevant functions can be described as "scope functions" and they are part of the Kotlin standard library: let, run, also, apply and with. You probably already heard about them and it's also likely that you even used some of them yet. Most people tend to have problems distinguishing all those functions, which is not very remarkable in view of the fact that their names may be a bit confusing. This post intends to demonstrate the differences between the available scope functions and also wants to discuss relevant use cases. Finally, an example will show how to apply scope functions and how they help to structure Kotlin code in…

08Mar 2018 by s1m0nw1 2 Comments

Publish Kotlin Library on Bintray using Gradle Kotlin DSL and Travis CI

Gradle, Java, Kotlin, Software Development, Tutorial

Distribute a Library on Bintray using Gradle Kotlin DSL In my latest blog post, published a few weeks back, I informed about the usage of the Gradle Kotlin DSL and how it helps with describing build scripts. In another earlier post, I introduced a small library that can be utilized for simplifying the creation of TLS/SSL sockets using a custom Kotlin DSL: SeKurity. In this post, we'll investigate how such a library can be made available to others that actually want to make use of it inside other projects. Ultimately, it should be possible to list the SeKurity library as a simple dependency in a build script like Maven or Gradle. Since the library itself is already backed by Gradle, I'll show a way of publishing the resulting artifacts at…

31Jan 2018 by s1m0nw1 5 Comments

Kotlin Tutorial – Quick Reference – Getting Started with Kotlin

Functional Programming, Kotlin, Software Development, Tutorial

Introduction Disclaimer: This reference has originally been published as a DZone Refcard. Kotlin has become one of the most popular JVM languages in the past few months. One special reason is that it experienced a lot of attention in the Android community after Google made Kotlin an official language for Android development. Kotlin is being developed by JetBrains, who are responsible for the most famous IDEs out there, most notably IntelliJ IDEA. Nevertheless, it's an open source language, which can be found on GitHub. The language is said to be very concise, safe in terms of error frequency, interoperable with Java and also offers many features that enable functional programming, writing type-safe DSLs and much more. Beside the JVM, Kotlin can compile for most Android versions, down to machine code…

02Dec 2017 by s1m0nw1 4 Comments

The Power of Gradle Kotlin DSL

Functional Programming, Gradle, Kotlin, Software Development, Tutorial

-The following is based on Gradle 4.3.1- A few weeks ago I started migrating most of my Groovy-based gradle.build scripts to Kotlin-backed gradle.build.kts scripts using the Kotlin DSL. Why would I do that? Kotlin is my language of choice and I love the idea of using a single language to do all my work. I never learned programming with Groovy and only know the bloody basics, which always makes me think: "This can't be the best way to do things...". Kotlin, on the other hand, is a language I use on a daily basis and therefore I know how to use the language appropriately. Additionally, Kotlin is a statically-typed language, whereas Groovy isn't. IDEs are having hard times offering code completion and error detection at compile time when a Groovy…

23Nov 2017 by s1m0nw1 2 Comments

Web Applications with Kotlin ktor

Functional Programming, Kotlin, Software Development, Web

Introduction Disclaimer: This ktor article was originally published in the Dzone Web Development Guide, which can be downloaded here. When Google made Kotlin an official language for Android a few months ago at Google I/O, the language gained much popularity in the Android world quickly. On the server side though, Kotlin is not as broadly adopted yet, and some people still seem to be cautious when backend services are involved. Other developers say that Kotlin is mature enough and we can safely use it for any server application in which Java could play a role otherwise. If you want to develop web apps with Kotlin, you can choose from various web frameworks like Spring MVC/WebFlux, Vert.x, Vaadin and basically everything available for the JVM. Besides the mentioned frameworks there's also…

27Oct 2017 by s1m0nw1 15 Comments

Kotlin Features I miss most in Java – Kotlin vs Java

Functional Programming, Java, Kotlin, Software Development

PLEASE find an updated version of this on my Medium: https://medium.com/@s1m0nw1/the-7-features-i-miss-most-when-going-back-to-java-after-spending-time-with-kotlin-2b3a35e0b13f. Let's write an article that covers "Kotlin vs Java" topics - I want to tell you which Kotlin features I miss most when going back to Java. My Life as a Java Dev Although I'm a big supporter of the Kotlin programming language, I still do a lot of Java programming on a daily basis for my employer. Since I'm aware of the great functionalities of Kotlin, I'm often struggling with Java as it has some "pitfalls", requires additional boilerplate and misses many features. In this post, I'd like to describe which Kotlin features I miss most when coding in Java. new and Semicolon Ever since I'm doing Kotlin, there are two things I always forget when coding in…