Three simple steps
How to use this tool?
This free online converter translates Java source code into Kotlin in three simple steps.
- Step 1
Add your Java code
Type, paste, or upload the Java code you want to translate.
- Step 2
Convert the code
Click Convert to translate the source code into Kotlin.
- Step 3
Review the result
Review, copy, or download the resulting Kotlin code from the output editor.
See it in action
Examples of Java to Kotlin conversion
These examples show Java source code and the corresponding Kotlin translation. Generated results can vary as AI models are updated.
Example 1
Is String Palindrome
Program that checks if a string is a palindrome or not.
Java code
Kotlin code
Example 2
Even or Odd
A well commented function to check if a number if odd or even.
Java code
Kotlin code
Language comparison
Key differences between Java and Kotlin
| Characteristic | Java | Kotlin |
|---|---|---|
| Syntax | Java has a verbose syntax with a lot of boilerplate code, whereas Kotlin has a concise and expressive syntax that reduces the amount of code needed to accomplish the same task. | Kotlin has a concise and expressive syntax that reduces the amount of code needed to accomplish the same task compared to Java. |
| Paradigm | Java is an object-oriented programming language that supports imperative and declarative programming paradigms, whereas Kotlin is a statically-typed programming language that supports both object-oriented and functional programming paradigms. | Kotlin is a statically-typed programming language that supports both object-oriented and functional programming paradigms. |
| Typing | Java is a statically-typed language, which means that the type of a variable is determined at compile-time, whereas Kotlin is also a statically-typed language but supports type inference, which means that the type of a variable can be inferred by the compiler. | Kotlin is a statically-typed language that supports type inference, which means that the type of a variable can be inferred by the compiler. |
| Performance | Java has a reputation for being fast and efficient due to its Just-In-Time (JIT) compiler, which compiles bytecode into machine code at runtime. Kotlin also has good performance, but it is slightly slower than Java due to its additional features. | Kotlin has good performance, but it is slightly slower than Java due to its additional features. |
| Libraries and frameworks | Java has a vast collection of libraries and frameworks, including Spring, Hibernate, and Struts, which are widely used in enterprise applications. Kotlin can also use these libraries and frameworks, but it also has its own set of libraries and frameworks, such as Ktor and Anko. | Kotlin can use Java's vast collection of libraries and frameworks, but it also has its own set of libraries and frameworks, such as Ktor and Anko. |
| Community and support | Java has a large and active community with a wealth of resources and support available, including documentation, forums, and tutorials. Kotlin's community is growing rapidly, but it is still smaller than Java's. | Kotlin's community is growing rapidly, but it is still smaller than Java's. However, there are still a wealth of resources and support available, including documentation, forums, and tutorials. |
| Learning curve | Java has a steep learning curve due to its verbose syntax and complex concepts, such as object-oriented programming and memory management. Kotlin has a much gentler learning curve due to its concise syntax and ease of use. | Kotlin has a much gentler learning curve than Java due to its concise syntax and ease of use. |
Common questions
Frequently Asked Questions
How do I convert Java to Kotlin?
Paste your Java code into the input box, confirm the languages are set to Java and Kotlin, and click Convert. CodeConvert AI analyzes your Java code and generates equivalent Kotlin code in seconds, preserving the original logic and structure.
What are the main differences between Java and Kotlin?
Java and Kotlin differ in syntax, type system, standard libraries, and common idioms, so copying code line for line usually will not compile. The converter maps each Java construct to its closest Kotlin equivalent. See the comparison table below for the key differences between Java and Kotlin.
Is the converted Kotlin code accurate?
The AI produces high-quality Kotlin code that preserves the behavior of your original Java code and follows Kotlin conventions. It handles common patterns, data structures, and idioms for both Java and Kotlin. For large or performance-critical code, review and test the Kotlin output before using it in production.
Can I convert an entire Java project to Kotlin?
You can convert Java files one at a time by pasting each file's code. For a full migration, convert each file and then review how classes, dependencies, and project structure map from Java to Kotlin. Signing in for free raises the input limit to 25,000 characters per conversion for larger files.
Can I convert Kotlin back to Java?
Yes. CodeConvert AI converts in both directions, so you can convert Kotlin to Java just as easily using our Kotlin to Java converter. Try the Kotlin to Java Converter
Is the Java to Kotlin converter free, and do I need to install anything?
Yes, it is free and runs in your browser with nothing to install and no IDE extension required. You can convert Java to Kotlin without an account for up to 2 conversions per day. Sign in for free for higher limits.
What are the benefits of signing in?
Signing in unlocks CodeConvert AI's Pro converter with more powerful AI models, a built-in chat assistant, code execution, saved conversion history, and personal notes. Every free account includes 5 credits and supports up to 25,000 characters of input per conversion, with no credit card required.
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