java-to-kotlin

name	java-to-kotlin
description	Convert Java code to Kotlin, including Java API comments from Javadoc to KDoc. Use when asked to migrate Java files, classes, methods, nullability semantics, or common Java patterns into idiomatic Kotlin while preserving behavior.

🪄 Converting Java code to Kotlin

• Java code API comments are Javadoc format.
• Kotlin code API comments are in KDoc format.

Javadoc to KDoc conversion

• The wording of original Javadoc comments must be preserved.

Treating nullability

• Use nullable Kotlin type only if the type in Java is annotated as @Nullable.

Efficient Conversion Workflow

• First, analyze the entire Java file structure before beginning conversion to understand dependencies and class relationships.
• Convert Java code to Kotlin systematically: imports first, followed by class definitions, methods, and finally expressions.
• Preserve all existing functionality and behavior during conversion.
• Maintain original code structure and organization to ensure readability.

Common Java to Kotlin Patterns

• Convert Java getters/setters to Kotlin properties with appropriate visibility modifiers.
• Transform Java static methods to companion object functions or top-level functions as appropriate.
• Replace Java anonymous classes with Kotlin lambda expressions when possible.
• Convert Java interfaces with default methods to Kotlin interfaces with implementations.
• Transform Java builders to Kotlin DSL patterns when appropriate.

Error Prevention

• Pay special attention to Java's checked exceptions versus Kotlin's unchecked exceptions.
• Be cautious with Java wildcards (? extends, ? super) conversion to Kotlin's out and in type parameters.
• Ensure proper handling of Java static initialization blocks in Kotlin companion objects.
• Verify that Java overloaded methods convert correctly with appropriate default parameter values in Kotlin.
• Remember that Kotlin has smart casts which can eliminate explicit type casting needed in Java.

Documentation Conversion

• Convert @param to @param with the same description.
• Convert @return to @return with the same description.
• Convert @throws to @throws with the same description.
• Convert {@link} to [name][fully.qualified.Name] format.
• Convert {@code} to inline code with backticks (`).

Final step: ensure the version is bumped

After the conversion is verified, invoke /version-bumped so the branch carries a strictly greater version.gradle.kts than the base ref before any ./gradlew build (which may transitively publishToMavenLocal and overwrite the previously published snapshot consumer repos depend on). The skill is a no-op when a bump already happened earlier on the branch.