When it comes to Android mobile app development, Java is the favorite language for many developers because Android is written in Java. Java is an object-oriented programming language that boosts the title of the second most active language on GitHub.
Java is very flexible, easy to learn and understand so that you can run it in a browser window or virtual machine. Android relies on Java and it is a good choice for cross-platform apps. Java has a large open source ecosystem, partly as a result of Google’s adoption of the Java Virtual Machine (JVM) for Android.
While Kotlin offers many advantages that Java doesn’t, it still has some shortcomings. Kotlin is 100% interoperable with Java and the two languages have lot of similarities in their structures. Both are object-oriented and statically typed and Kotlin has been designed to solve the problems to the ones that Java solves.
However Kotlin is a truly modern and powerful language with a much cleaner syntax that helps to solve common headaches such as source code verbosity and run time exceptions. Working side by side with Java on Android, you can add Kotlin code to your existing projects and can call Java code from Kotlin and vice versa.