Most Android applications are written in Java. Kotlin is also supported and interoperable with Java. For ease, for the rest of this workshop, when I refer to “Java”, you can assume that I mean “Java or Kotlin”. Instead of the Java code being run in Java Virtual Machine (JVM) like desktop applications, in Android, the Java is compiled to the Dalvik Executable (DEX) bytecode format. For earlier versions of Android, the bytecode was translated by the Dalvik virtual machine. For more recent versions of Android, the Android Runtime (ART) is used.
If developers, write in Java and the code is compiled to DEX bytecode, to reverse engineer, we work the opposite direction.