What are the differences between C# and Java?
In this article, we’ll be comparing the merits of two popular programming languages side-by-side: C# and Java. At their core, C# (pronounced see sharp) and Java are both robust, high-level, object-oriented programming languages with more similarities than differences. One significant advantage to learning either language is that their fundamental similarities make it relatively easy to learn one language after mastering the other.
Together, we’ll look at a brief history of the two programming languages in question, their different applications, strengths, and what resources to explore to deepen your understanding of C# and Java.
Let’s jump right in!
C# and Java: A brief history#
Origins of C##
C# was first developed in 2000 as a direct competitor to Java by Anders Hejlsberg and his team at Microsoft. Like Java, C# was based on the C and C++ programming languages, referenced by its original name, “C.O.O.L.,” or “C-like Object Oriented Language,” but was designed with business and enterprise needs in mind.
In 2005, version 2.0 of C# introduced features generics and iterators to catch up to Java. Version 2.0 also introduced other major features such as partial types, anonymous methods, nullable value types, covariance, and contravariance. Though the first few versions of C# shared many similarities with C++ and Java, later releases helped distinguish C# as a unique language capable of facilitating object-oriented and functional programming.
Although C# was originally closed-source and exclusive to development in the Microsoft ecosystem, new features and open-source tools were added to support cross-platform development.
Origins of Java#
James Gosling began the development of Java at Sun Microsystems (later acquired by Oracle) as an alternative to the C++ programming language, with its first public implementation in 1995.
Java’s design requirements were centered around enabling the creation of robust and secure applications across multiple platforms while consuming the least amount of system resources. In addition, Gosling sought to create a language platform that would be simple and familiar to programmers, allowing them to grasp the fundamental concepts of the language quickly.
What emerged was a highly reliable, open-source programming language that has proven ideal for developing network-based end-user applications across a wide range of environments.
Overview and applications: C# vs. Java#
What is C#?#
C# is a high-level, general-purpose, object-oriented, and notably, it is the first component-oriented programming language. Like Java, C# is popular because it is versatile, easy to learn, and enjoys the support of a large community that has made many contributions to developing new C# tools and software.
As a multi-paradigm programming language, C# supports object-oriented programming in addition to functional, structured, imperative, reflective, and concurrent programming paradigms.
C# programs run on the .NET Framework, which has two main components:
- .NET Framework
- .NET Framework Class Library (FCL)
- Frameworks
- Utility features written in .NET
- Wrappers around OS functionality
- Common Language Runtime (CLR)
- .NET Framework Class Library (FCL)
The .NET Framework class library (FCL) is a collection of different classes, interfaces and data types used to design .NET applications.
The Common Language Runtime (CLR) uses just-in-time (JIT) compilation to compile the C# code used for .NET applications.
Common applications of C#:
- Game development
- Microsoft applications
- Web applications
- Desktop applications
- …and more!
What is Java?#
Java is a high-level, general-purpose, object-oriented programming language. Java is popular amongst application developers because of its simplicity, versatility, and portability. Thanks to its large and well-established community, anyone looking to start a Java project will find that they have access to a massive collection of useful open source libraries and tools.
The Java Platform or Java Development Kit (JDK), is the software development environment used to build and run Java applications and components. The JDK can be deployed on Windows, macOS, Linux, and Solaris.
You can think of the Java Platform as a series of nested packages:
- Java Development Kit (JDK)
- Java Runtime Environment (JRE)
- Java Virtual Machine (JVM)
- Libraries
- Development tools (javac, java, etc.)
- Other files
- Java Runtime Environment (JRE)
The Java Runtime Environment (JRE) is an installation package that sets up an environment where you can only run a Java program or application. The JRE contains class libraries, loader classes, and the JVM.
The Java Virtual Machine (JVM) is an interpreter and provides a runtime environment for your code. The JVM is a critical part of both the JDK and JRE, as it is responsible for going through each line of a Java program to execute it.
Common applications of Java:
- Front-end web development
- Back-end web development
- Mobile applications
- Big data analytics
- Scientific computation applications
- Machine learning
- Data science
- …and more!
Comparing C# and Java#
Similarities#
For the most part, C# and Java are reasonably similar because they’re both high-level, object-oriented programming languages descended from C and C++.
C# and Java share:
- Similar syntax (e.g., static, class, int)
- Advanced features like garbage collection
- Multiple class inheritance
- Cross-platform functionality
- Intermediate language code generation
- C# compiler generates Microsoft Intermediate Language (MSIL)
- Java compiler generates Java bytecode
- OOP concepts
- Encapsulation
- Abstraction
- Inheritance
- Polymorphism
Comparison chart: C vs. Java#
| Features of comparison | C# | Java |
|---|---|---|
| Programming paradigm | Object-oriented, component-oriented, functional, strong typing | Object-oriented |
| Runtime environment | Common Language Runtime (CLR) | Java Virtual Machine (JVM) |
| Platform dependency | Cross-platform (Windows preferred) | Cross-platform |
| Checked exceptions | Not supported | Supported |
| Enumerations | Supported with the yield statement |
Not supported |
| Pointers | Supported in unsafe mode | Not supported |
| Conditional compilation | Supported | Not supported |
| Structure and union | Supported | Not supported |
| Arrays | Specialization of Object | Specialization of System |
goto statement |
Supported | Not supported |
strictfp keyword |
Not supported | Supported |
Which language should I learn?#
Although C# and Java share enough similarities that it won’t put you at a disadvantage to learn one and not the other, each language does possess certain strengths that are important to take into consideration.
Here are some questions to ask when deciding between C# and Java:
- What platform am I developing on?
- What types of applications will I be making?
- Is there a tool I want to use?
- Are there industry-specific preferences?
- Does the company I want to work for have a preference?
Consider learning Java first if you want to create highly complex web applications or work with Android apps. Also, let’s not forget that Java’s slogan is “Write once, run anywhere”! If portability is a top priority, Java is a clear winner. On the other hand, if you plan on developing games or working in the Microsoft ecosystem, it may be more advantageous to start out with C#.
Platform evolution: .NET and Java in 2026#
The runtime environments for both C# and Java have changed significantly since the early days. It’s important to understand their modern form:
.NET today: The classic .NET Framework has evolved into .NET (5, 6, 7, 8, and beyond) — a unified, cross-platform, open-source runtime. It supports Windows, macOS, Linux, containers, and cloud-native workloads, and includes tools like ASP.NET Core, Entity Framework Core, and MAUI for building cross-platform apps.
Modern JVM: Java still runs on the Java Virtual Machine (JVM), but the ecosystem now includes modern tooling like GraalVM for high-performance execution, custom runtime creation with jlink, and container-optimized builds. The JVM has also seen performance and startup-time improvements, especially for microservices and serverless environments.
Why it matters: Many older comparisons frame .NET as Windows-only and Java as “write once, run anywhere.” In 2025, both are truly cross-platform, cloud-native, and optimized for modern workloads.
New language features you should know#
Both languages have introduced major new features that make them more powerful and expressive:
Java:
Virtual threads (Java 21) simplify concurrency with lightweight threads.
Record classes provide concise, immutable data structures.
Pattern matching for switch makes control flow more expressive and readable.
C#:
Records allow immutable data modeling with minimal boilerplate.
Nullable reference types improve type safety and reduce runtime errors.
Pattern matching enhancements make code more concise and functional.
Why it matters: These features reduce boilerplate, improve safety, and modernize both languages for concurrent, data-driven, and API-heavy applications.
Concurrency and performance: Loom vs async/await#
Concurrency is a major consideration when choosing a backend language:
Java’s virtual threads (Project Loom): Enable millions of lightweight threads on the JVM, making high-concurrency applications simpler and more scalable without complex frameworks.
C# async/await: Uses the Task Parallel Library (TPL) to simplify asynchronous programming, offering strong integration with the .NET runtime and ecosystem.
Verdict: Both ecosystems now offer developer-friendly concurrency models, but Java’s virtual threads represent a significant leap forward in scalability, while C# remains slightly more ergonomic for asynchronous workflows.
Serverless, cloud, and AOT compilation#
Modern deployment environments — from serverless to containers — care about startup time and footprint. Both platforms have evolved to meet these needs:
.NET: Offers NativeAOT for building ahead-of-time compiled applications with instant startup times — ideal for serverless functions and microservices.
Java: Tools like GraalVM Native Image compile Java apps into native executables, drastically improving cold-start times and resource usage.
Why it matters: Choosing between C# and Java may now come down to deployment needs — for example, .NET may be slightly easier to AOT-compile out of the box, while Java’s GraalVM offers broader performance tuning options.
Modern ecosystem and use cases#
How these languages are used in 2025 is different from just a few years ago:
Java: Dominates in enterprise software, banking, big data platforms (Hadoop, Spark), distributed systems, and cloud backends. Still widely used in Android development, though Kotlin is now the preferred language.
C#: A top choice for cloud APIs, enterprise services, desktop apps, and cross-platform UI with .NET MAUI. It’s also the backbone of Unity, making it the go-to language for game development.
Why it matters: Your choice should align with ecosystem strengths — Java excels in enterprise-scale distributed systems, while C# thrives in enterprise, game development, and cross-platform application scenarios.
Distribution, licensing, and support#
Not all “Java” and “.NET” builds are the same. In 2025, you have more distribution and support options:
Java: OpenJDK is free and open-source, but vendors like Eclipse Temurin, Amazon Corretto, and Azul Zulu offer commercial support, security updates, and performance tuning.
.NET: Fully open-source and free under the MIT license. Microsoft provides commercial support for enterprise users, and long-term support (LTS) releases arrive every two years.
Why it matters: Licensing, support, and security updates can influence total cost of ownership — especially for enterprise or regulated environments.
When to choose C# vs Java in 2026#
Here’s a quick decision guide based on project needs:
Scenario | Best Choice |
Building large-scale enterprise apps with complex concurrency | Java (virtual threads, mature enterprise stack) |
Cross-platform APIs and cloud microservices | C# (ASP.NET Core, excellent container support) |
Game development or real-time simulations | C# (Unity ecosystem) |
Data processing, big data, or JVM-based tooling | Java (Hadoop, Spark, Kafka) |
Cross-platform desktop/mobile apps | C# (.NET MAUI) |
Ultra-fast startup serverless functions | Both (NativeAOT for C#, GraalVM for Java) |
Wrapping up and next steps#
If you want to learn to code in C# or Java, check out our courses and learning paths! Educative’s learning paths are designed to help you develop valuable, practical skills at your own pace with interactive challenges and exercises.
- Java for Programmers is a great way to familiarize yourself with the Java programming language. This course is perfect for people who have programming experience but are new to Java.
- C# for Programmers: A Practical Guide introduces you to fundamental programming concepts found in C#, such as loops, arrays, and object-oriented programming.
Happy learning!
