Can I get some reasons to use Java instead of Kotlin?

Well, let me answer the opposite question.

If you're targeting the JVM, and don't mind the stdlib dependency, then the best reason to use Kotlin is because you like the language; its Java interop is essentially complete (100% from Kotlin to Java, some extra work needed for Java to Kotlin).

The other reason to use Kotlin is for targeting multiple platforms (JVM, Android, web, and native). The JDK doesn't provide an equivalent, but there are alternative compilers in various states of viability (Graal, GCC, numerous WASM projects).

Otherwise the differences between languages are mostly overblown.

I've used both. I like both. I have a slight preference for Java. I'm not going to try and convince people one way or another. Most languages have their good and bad points