Java to .NET

Free Java to .NET Code Converter

No email required. 100% free. Done in 30 seconds.

Transform your code from Java to .NET with our free AI-based code convertion tool. If you like what you see, we also create documentation for your code! We don't ever store your code or any representation of it in our databases, but it will be shared with the LLM of our choice for processing.

Other tools






Ionic + Angular










React Native


Ruby on Rails






How to convert from Java to .NET

Migrating from Java to .NET can seem daunting for those less familiar with .NET, but the process is manageable with a clear plan and an understanding of both frameworks. Here is a comprehensive guide to help proficient Java developers smoothly transition to .NET.

Understanding the Key Differences

Language Differences

Java and .NET have syntactic and operational differences. Java is a statically-typed, object-oriented language, while .NET primarily uses C#. Both languages are similar in how they handle basic constructs like loops and conditionals, but they diverge in terms of libraries and some syntax.

Environment and Runtime

Java runs on the Java Virtual Machine (JVM), making it platform-independent. .NET, particularly with .NET Core, has similar cross-platform capabilities but typically runs on the Common Language Runtime (CLR).

Initial Setup for .NET Development

Setting Up Your Environment

To get started, you need to install the .NET SDK and an Integrated Development Environment (IDE) like Visual Studio or Visual Studio Code. This setup will enable you to properly compile and run .NET applications.

Project Conversion Tools

There are some tools available that can help automate parts of the conversion. However, you must not rely on them entirely as manual adjustments will be necessary for nuances and specific use cases.

Converting the Java Codebase to C#

Class Structures and Syntax

When converting Java classes to C#:

  • Java: public class MyClass { ... }
  • C#: public class MyClass { ... }

Basic syntax, such as class definitions, remains relatively unchanged. Still, you need to pay attention to some language-specific features, such as access modifiers and data types.

Data Types and Variables

In Java, a variable declaration looks like this:

int num = 10;
String str = "Hello";

In C#, it becomes:

int num = 10;
string str = "Hello";

Note that String in Java is equivalent to string in C#. It's a small change but important for accurate code conversion.

Handling Libraries and Frameworks

Java uses libraries such as Apache Commons or Google's Guava. In .NET, you will use different libraries like .NET's System namespace or third-party libraries available through NuGet. Replace Java-specific libraries with the .NET equivalents in your project.

Detailed Code Conversions

Exception Handling

Both Java and C# support try-catch blocks, although their implementation slightly varies:

  • Java:
    try {
        // code
    } catch (Exception e) {
  • C#:
    try {
        // code
    } catch (Exception e) {

Collections and Data Structures

The Java Collections Framework, such as ArrayList, HashMap, etc., corresponds to .NET’s List<T>, Dictionary<TKey, TValue>, etc.

  • Java:
    List<String> list = new ArrayList<>();
  • C#:
    List<string> list = new List<string>();

Asynchronous Programming

Java typically uses multithreading with Thread objects or the java.util.concurrent package. In .NET, asynchronous programming is often accomplished with async and await keywords.

  • Java:
    new Thread(() -> {
        // code 
  • C#:
    async Task MyMethod() {
        await Task.Run(() => {
            // code

Testing and Debugging

Testing frameworks in Java, such as JUnit, have .NET equivalents like NUnit or MSTest. Familiarizing yourself with these frameworks will be crucial for ensuring your .NET code is as reliable as your Java code.

Performance Considerations

When migrating to .NET, consider that performance optimizations in Java may not directly translate. Use performance profiling tools available in Visual Studio to identify bottlenecks and optimize accordingly.

Final Touches

Refactoring and Optimization

Once the code is converted and initially tested, undertake a thorough refactor to optimize and adhere to .NET best practices. Utilize .NET's powerful LINQ capabilities and other features unique to the .NET ecosystem.

Documentation and Code Reviews

Ensure that all code is well-documented and reviewed by peers familiar with .NET. Code reviews are invaluable for catching potential pitfalls and areas for improvement.


Migrating from Java to .NET involves several steps and careful consideration of both language and framework differences. By understanding these nuances and utilizing available tools, proficient Java developers can successfully convert their Java codebase to .NET. This guide should serve as a solid foundation for your transition, making the process smoother and more efficient.

Document your code using AI

Sign up now
& free your developers' time

Start for free

Join thousands of companies documenting their code using AI.

Frequently Asked Questions

This free AI tool does its best to generate professional documentation. However, it's missing some context from other related files. The paid version takes into account different files to generate documentation for each use case, apart from the documentation of every file. You have also the possibility of add custom concepts to improve the knowledge of your codebase.

No. You don't have to enter any personal information to use Codex's free code documentation tool — it's 100% free.

No. An encrypted version of your code is stored only while its being processed and it's deleted immediately.

If you can work with a custom Azure model in your own account, let us know. If not, Codex also works with open source models that can run on-premises, on your own servers, so your data is always yours. Feel free to get in touch with us!