Can you name features and capabilities of Kotlin that are not present in Java?

Kotlin offers a number of features absent in Java that make development more convenient and safer:

• Null safety: built-in type system that prevents NullPointerException at compile time.
• Extension functions: ability to add new functions to existing classes without inheritance.
• Coroutines: a convenient way to write asynchronous and non-blocking code.
• Data classes: automatic generation of equals, hashCode, toString, and copy methods for classes intended to hold data.
• When expression: a more powerful and expressive alternative to switch.
• Lambda expressions with receiver (DSL): allow creating convenient DSLs within code.
• Smart casts: automatic type casting after a check.

Example of a data class and an extension function:

data class User(val name: String, val age: Int)

fun String.isEmail(): Boolean = this.contains("@")

val user = User("Alice", 30)
println(user)
println("test@example.com".isEmail())