An AI answer about Kotlin looks convincing until you run it. Here, examples run right in the app, so you see the real output, not a guess.
Tap Run and the real output appears right under the code, so you know what it does before it goes into your project. No Kotlin to install, no IDE, no setup, no account.
390+ short examples, one task each. Over 95% run on Kotlin 2.4.
You know what you need, but not the exact syntax:
• How do I fall back to a default value when a variable is null?
• How do I return two values from a function?
• How do I merge two maps?
Each has a working example here.
• 24 sections, including strings and dates, collections, nullable types, classes and interfaces, enums, generics, extension functions, lambdas, exception handling, regular expressions, multithreading, files, JSON and XML, algorithms, and design patterns.
• What changed from Kotlin 1.4 to 2.0, with before-and-after code: value classes, sealed interfaces, data objects and the improved smart casts in Kotlin 2.0.
• Reference, 320+ entries: keywords and standard library functions for strings, collections, files, and coroutines. Tap a word in the code to look it up.
• 200+ SQL queries: JOIN, GROUP BY, subqueries, window functions; more than half run on a practice database.
• Search looks inside the code: type joinToString to find every example that uses it.
• Edit an example and run your version, or write your own.
• Works on iPhone, iPad, and Mac.
• Everything except running code works offline.
Free version: 210+ Kotlin examples and 120+ SQL queries, the full reference, and 12 runs and 12 edits a day (Kotlin and SQL runs share one limit). Full version: all examples and queries, unlimited edits and examples of your own, and up to 30 Kotlin and 80 SQL runs a day. One-time purchase, no subscription.
Built by a developer for developers. The project behind it has been in active development since 2015.
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• Run code right in the app: tap Run and the real Kotlin 2.4 output appears under the example. You can also edit an example and run your version.
• Kotlin keyword and function reference with 320+ entries. Tap a word in the code to look it up.
• New section: what changed from Kotlin 1.4 to 2.0, with before-and-after code.
• Improved support for foldable phones and large screens.
Version 4.10
The developer, Fedor Obraztsov, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Privacy practices may vary based, for example, on the features you use or your age. Learn More
The developer indicated that this app supports the following accessibility features. Learn More
Fedor Obraztsov has not identified itself as a trader for this app. If you are a consumer in the European Economic Area, consumer rights do not apply to agreements between you and the provider.