learn "modern" Java?

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"modern" Java

println("👋 Hello, Java ");

instead of "classic" Java

public class HelloWorld {
public static void main(String[] args) {
System.out.println("Hello, World!");
}
}

With competition like Kotlin, Scala, Dart, C#, Python, Mojo, Go...
even TypeScript as "enterprise" language... 
What keeps Java relevant except existing codebase?
Like COBOL... will be around for long time... modern or not...