It took 3+ weeks, start with a basic online assessment, then having a talk with the project manager and tech leader, they are friendly and good guys, asked about ' will you do React native in the future' ? tech question like explicit implicit intent, dimension of Gradle, how to inject a ViewModel into fragment by using Dagger2, do you know about JVM, JNI... ^^, I used JNI a few years ago before but I didn't even remember its name 'JNI', really have no idea what is the meaning of these tech question. and their Android apps seem never been encrypted and obfuscated, not surprised that lots of things could do better in that project.