In general, because of the May 2019 announcement from Google I would recommend beginners at Android app development start with Kotlin however there are some exceptions where I think Java may be better. There are two scenarios I would recommend learning Java first for Android app development as a beginner.
Read moreHow long does it take to learn Kotlin from Java?
Offered by JetBrains, it will take 25 hours to complete the course and switch to Kotlin from Java programming.
Read moreDo you need Java to learn Kotlin?
Knowledge of Java is not a must . As I see, Kotlin borrowed something from Python and other languages, so you will not feel yourself altogether lost trying to get acquainted with it.
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