Production checklist

Last reviewed Jun 1, 2026 Content v20260601

Track mode

server_compiled

Means

Compiled runner

Reading

~2 min

Level

advanced

This lesson

This lesson teaches Production checklist: the syntax, patterns, and safety habits you need before advancing in Kotlin.

Teams still ship Production checklist in Kotlin codebases—skipping it leaves gaps in debugging and code reviews.

You will apply Production checklist in contexts like: Android apps, Spring services, and shared KMP modules.

Write Kotlin in main.kt with fun main(), click Run on server—the dev runner kotlinc compiles to a JVM jar and java runs it; use println for output (requires JDK + kotlinc; LEARNING_RUNNER_ENABLED=true).

When pointers, structs, and basic control flow from intermediate lessons are familiar.

Shipping Kotlin on JVM or Android means more than correct syntax—configure static analysis, tests, dependency scanning, logging, and coroutine discipline for services and mobile releases.

Checklist

Enable -Xexplicit-api or strict module boundaries for libraries when appropriate
Detekt/ktlint in CI; treat warnings as debt with a burn-down plan
./gradlew test on every PR; JVM tests plus Android instrumented tests where applicable
Pin Kotlin, Gradle, and AGP versions; run dependency vulnerability scans
Structured logging (slf4j/logback), not raw println in production servers
Never block Main dispatcher; avoid runBlocking on request threads
Document Java interop boundaries with nullability annotations for APIs
ProGuard/R8 rules reviewed when shrinking Android releases

Important interview questions and answers

Q: Why Detekt in CI?
A: Enforces style and complexity rules Kotlin compiler does not catch—keeps coroutine and API mistakes visible in review.
Q: runBlocking in production?
A: Avoid on threads serving users—use suspend endpoints; runBlocking is for main() bridges and tests only.

Self-check

Name two tools for Kotlin static analysis.
Why avoid println in server production?

Track summary

You covered Kotlin from syntax and null safety through OOP, collections, functional features, generics, delegation, exceptions, coroutine concepts, stdlib idioms, Gradle tooling, file I/O, testing, Java interop, Android context, and interview habits. Kotlin's sweet spot is Android, JVM services with Java libraries, and teams wanting safer, concise code on existing JVM investments.

Next steps

Build a small Gradle CLI or Ktor HTTP service with tests
Open Android Studio and complete a Compose tutorial locally
Add kotlinx-coroutines and practice runTest with Flow collectors
Compare patterns with Java, Go, and C# tracks
Read official Kotlin docs on coroutines and multiplatform when expanding beyond JVM

Tip: This lesson closes the track with summary and next steps—run Detekt and ./gradlew test before shipping.

Interview prep

Detekt purpose?: Static analysis for style, complexity, and coroutine misuse beyond compiler.
CI must run?: ./gradlew test, lint/detekt, dependency scanning; avoid runBlocking on workers.

Playground

Runs on the configured server runner (dev: npm run runner with LEARNING_RUNNER_ENABLED=true). Output appears below the editor.

Code runner not available

Server runner is disabled. Set LEARNING_RUNNER_ENABLED=true and LEARNING_RUNNER_URL in .env (see .env.example).

Discussion

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Starter discussion topics

Detekt ktlint?
KMP next step?

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