To write this app, there aren't many requirements. Except for Kotlin and Java, you should also have Gradle installed. You can use any IDE you wish, but again IntelliJ IDEA Community Edition is recommended, as it works great with Kotlin and is completely free.

Finally, the dictionary words we will be using are already included with the code files that you can download from https://github.com/PacktPublishing/Kotlin-Quick-Start-Guide. They are in JSON format, with terms and definitions as JSON key-value pairs. The dictionary is free to use thanks to project Gutenberg: http://www.gutenberg.org/.

JavaFx will be our GUI library. JavaFx is a successor to the Java Swing framework and with version 8, it's part of the Java SDK and JRE. There is no need for prior knowledge of JavaFx; although the library and its API are rather big, we'll be explaining the basics as we work on the UI part of the app.