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C#vsJava
What is the difference between C# and Java?
Updated 2 min read7 differences
In short
C# and Java are similar statically typed, garbage-collected languages; C# runs on Microsoft's .NET, Java on the JVM, and each has its own ecosystem.
C#
C# is a statically typed, object-oriented language that runs on the .NET runtime with garbage collection and is used for web backends, desktop apps, and games.
Read the page on C#Java
Java is a statically typed, object-oriented programming language that compiles to bytecode for the Java Virtual Machine, so programs run on many platforms.
Read the page on JavaC# and Java compared
| Aspect | C# | Java |
|---|---|---|
| Runtime | The .NET runtime (CLR) | The Java Virtual Machine (JVM) |
| Origin | Microsoft, released in 2002 | Sun Microsystems, released in 1995; now Oracle and OpenJDK |
| Language features | Properties, LINQ, struct value types, nullable reference types | Records, sealed classes, pattern matching, virtual threads |
| Generics | Kept at runtime (reified) | Erased at runtime |
| Web framework | ASP.NET Core | Spring Boot, Quarkus, Micronaut |
| Strong areas | Business software, web APIs, games, Windows desktop apps | Enterprise backends, big data, Android |
| Packages | NuGet | Maven Central, through Maven or Gradle |
The difference, explained
Java, released by Sun Microsystems in 1995, and C#, released by Microsoft in 2002 as part of .NET, look and feel very similar. Both are statically typed, object-oriented and garbage-collected, both compile to bytecode for a managed runtime, and both use C-style syntax with classes, interfaces and generics. Someone who knows one can usually read the other within days.
C# has often added language features earlier and more freely. It has properties, LINQ queries, async/await, custom value types with struct and nullable reference types, and it keeps generic type information at runtime, while Java erases it. Java has moved more carefully, with a strong focus on backward compatibility, and has added records, sealed classes, pattern matching and virtual threads in recent releases.
The ecosystems decide most choices. Java runs on the JVM, comes in builds of OpenJDK from many vendors, and is strong in enterprise backends, big-data tools and Android, with Spring Boot as its most common framework. C# runs on .NET, open source and cross-platform since 2016, with ASP.NET Core for web services, and it is the scripting language of several widely used game engines.
A common misconception is that C# is Windows-only. Modern .NET runs on Windows, macOS and Linux, in containers and in every major cloud. Another is that Java is slow; the JVM's JIT compiler makes long-running services very fast. Performance is close, and the choice usually follows the team's experience and the platform the company already uses.
Which one should you use?
Choose C# when…
- Your company already runs on Microsoft and .NET technologies.
- You build games in an engine that uses C#, or Windows desktop apps.
- You want features like LINQ and properties built into the language.
Choose Java when…
- You work in a JVM ecosystem with Spring or big-data tools.
- You want a choice of runtime vendors and long-term support releases.
- You need existing Java libraries or code shared with Android.
Readers ask
Is C# a copy of Java?
C# was clearly influenced by Java and C++, and early versions looked very similar. Since then the two have borrowed ideas from each other, and each has features the other lacks.
Which is faster, C# or Java?
They are close. Both use JIT compilers and modern garbage collectors, and benchmarks swing either way; how the code is written matters far more than the language.
Is it easy to switch between C# and Java?
Yes. The syntax, typing and object model are so similar that most of the learning is the other ecosystem: its libraries, frameworks and build tools.