@JvmField Annotation in Kotlin

Simplifying Interoperability with Java — Part 2

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👻 Hello dear Kotlin witches and warlocks! 🎃

As the moon rises and the shadows grow longer, it’s time to brew up another magical potion from the depths of Kotlin’s spellbook. Today, we summon the powers of @JvmField! 🧙‍♀️ This little-known incantation can turn your Kotlin properties into fields that even Java can access without chanting "getter" or "setter" spells.

Ready to conjure up some field magic? Let’s begin… 👻

Example with Data Class and @JvmField

Let’s summon a Kotlin data class that we want to expose to Java. Normally, Kotlin automatically generates getter and setter methods for each property.

data class User(
    var name: String = "Agatha",
    val age: Int = 550
)

When this Kotlin code is compiled to Java bytecode, it generates:

public class User {
    private String name = "Agatha";  // Backing field for `name`
    private final int age = 550;    // Backing field for `age`…