Java is primarily used as a programming language on Android. Java applications follow Write Once Run Anywhere (WORA) approach. The programming language has stood the test of time. Java is still popular among mobile app developers.
Kotlin has picked up popularity ever since Google has declared it as the preferred programming language for Android. Kotlin is known for its performance and scalability. Those with some background in Java can pick up Kotlin. The programming language is great for developers that wish to migrate to a newer language.
The programming language is designed by Apple as an official language for iOS and macOS development. Apple has been pushing Swift as a replacement to Objective-C. The open-source nature of Swift makes it a great choice for developers.
Rust can be used for developing apps that run on Android, iOS, Linux, and macOS. The programming language shares similar features as C, C++. The flexibility is an important function that makes Rust a popular choice. You can use Rust to develop native or web-based apps.
The front-end programming language, HTML5 can be used for creating web-based apps that run on any device. There are multiple web-based frameworks that use HTML5. The apps written with HTML5 can be placed in a wrapper for native app format. HTML5 offers the best of both worlds.