C# vs Java: A Detailed Comparison

C# and Java are two of the most popular and widely used programming languages in the world. Both hold a solid position when it comes to developing web applications, cloud apps, desktop applications, and back-end development in general. But there are notable differences between the two technologies. When you’re hiring for a software development project, […]

by Dilyan Dimitrov

October 28, 2023

7 min read

csharp vs java man surrounded by lines of code Image by standret on Freepik

C# and Java are two of the most popular and widely used programming languages in the world. Both hold a solid position when it comes to developing web applications, cloud apps, desktop applications, and back-end development in general.

But there are notable differences between the two technologies. When you’re hiring for a software development project, it’s important to understand what each of them is good at. In this article, we’re going to take a closer look at the difference in C# vs Java and help you make an informed decision for your project. 

What is C#?

C#, also known as C-sharp, was designed in 1999, and released in the year 2000 by Microsoft as part of their .NET program. It’s a general-purpose programming language intended to be modern, simple and intuitive to use. 

Popular IDEs for C# include Microsoft’s Visual Studio and the lighter Visual Studio Code. Their capabilities range from intelligent code completion and debugging tools to integrated testing and deployment solutions.

Some notable C# features are:

  • Strong typing: Data types are clearly defined at compile time, reducing the risk of errors. Applications are more stable and reliable. 
  • Component-oriented: C# is designed to support component-based programming, which serves to reduce development time and improve time-to-market. 
  • Modern syntax: Microsoft created a modern language syntax that’s easier to read and write, making it accessible to a wide range of programmers. 
  • Memory management: Automatic memory management prevents common memory-related issues and ensures software reliability and stability. 
  • Object-oriented: As an object-oriented programming (OOP) language, C# revolves around objects and classes. It’s designed for organized and maintainable code. 
  • Just-In-Time (JIT) compiler: The compiler translates CIL code into machine code, improving performance and efficiency

C# is used in a wide variety of domains. It’s a popular choice for game development, especially within the Unity game engine. At the same time, it’s the primary choice for Windows development, used for high-performance applications and services on the Windows platform. It can also craft dynamic, feature-rich web applications, often in combination with ASP.NET. And its integration with cloud computing technologies has solidified its position in the realm of cloud-based solutions.

C# is used to develop anything from desktop applications through web applications and services all the way to mobile applications on the .NET platform. It’s also popular in the game development community. 

What is Java?

Java is an object-oriented, class-based programming language. It was developed in 1995 by Sun Microsystems. Java’s core design principle is the concept of WORA – Write Once Run Anywhere. That makes it a platform-independent language. Java applications can run on any Java Virtual Machine, regardless of architecture and operating system.  

Java’s tooling includes IDEs like IntelliJ IDEA and Eclipse that provide extensive development support. Much like C# IDEs, they offer features like code analysis, intelligent code completion, and powerful debugging capabilities.

Some notable Java features include: 

  • Object-oriented: Like C#, Java follows an OOP approach, promoting a modular and organized codebase with a high level of maintainability. 
  • Exception handling: Java’s exception handling lets developers efficiently manage errors and recovers from potential issues. This leads to more robust software that can quickly recover from unforeseen challenges. 
  • Just-In-Time (JIT) compiler: The compiler translates Java bytecode into native machine code at runtime, which leads to faster, more responsive software. 
  • Multithreading: Tasks can be executed concurrently, giving Java applications a productivity boost. This is especially useful if a solution needs to handle multiple tasks at the same time. 

Java is a versatile programming language. It’s widely used to create scalable, secure enterprise applications for diverse business needs. It’s also the language of choice for Android app development. In the realm of web services and middleware, Java excels at creating high-performance, load-bearing solutions. Last but not least, it offers powerful networking capabilities, making it a great choice for distributed system development. 

C# vs Java: Performance and resource utilization

A programming language’s performance is naturally one of its most important aspects. Java and C# share some similarities and differences in that regard. Let’s look at some main areas of development performance and discuss how each language handles them: 

JIT compilation

As we saw in the sections above, both Java and C# utilize JIT compilation to enhance execution speed. They do, however, do that in slightly different ways. 


C# uses the RyuJT compiler. It takes intermediate C# code (also known as CIL, or Common Intermediate Language, and converts it into native machine code just before the program runs. It also offers tiered compilation, which means it can adjust its optimization based on how the code is going to be used. 


Java uses the HotSpot compiler. Instead of converting code at runtime, it uses a more dynamic, adaptive optimization approach. HotSpot observes the way code is used during runtime, then converts frequently-used code paths into native machine code. This adaptability lets Java applications run on various setups, in line with its Write Once Run Anywhere policy. 

Memory usage

Efficient memory usage is a key performance indicator in the programming world, related to faster execution times and lower resource consumption. Both Java and C# use garbage collection mechanisms to manage their memories. However, the way they do that differs. 

Java garbage collection

Java uses generational garbage collection. This approach hinges on the observation that most objects in a typical software solution have a relatively short lifespan. So, the collector divides heap memory into two generations: young and old.  

The young generation holds newly created objects. SInce many of them quickly become obsolete, the collector does what’s called “minor garbage collection” to identify and clean up the shortest-lived ones. 

Objects that survive multiple minor garbage collections become part of the old generation. Here, there are less frequent “major garbage collections”. They’re more time-consuming, and aim to free memory taken up by long-term objects. 

C# garbage collection

C#, on the other hand, has a mark-and-compact garbage collector. It works by continuously compacting memory to minimize fragmentation(and, therefore, reduce inefficiencies and performance degradation). 

There are two distinct phases in this approach. During the mark phase, the collector identifies and marks all objects that are in use. Essentially, this phase is about distinguishing between live and dead objects. Then, during the compact phase, the C# collector reclaims memory occupied by dead objects. Then it compacts live objects into a contiguous memory space. 

C# vs Java: platform support

Comparing C# and Java platforms is a difficult task. Both languages are immensely popular and offer the ability to create a wide range of applications across multiple platforms. 

Java platform support

Java, with its “Write Once, Run Anywhere” approach, has always been celebrated for its cross-platform capabilities. Through a Java Virtual Machine, Java applications can run on anything that supports a JVM, from Windows and macOS to Linux and beyond. 

C# platform support

C# was initially limited to Windows devices. However, thanks to frameworks like .NET Core and Xamarin, the language has significantly expanded its reach. C# developers today can also create for many platforms, including macOS, Linux, Android and iOS. 

C# vs Java: security

Java and C# share a strong focus on security. Both languages are strongly typed, which means data types are clearly defined to reduce the risk of type errors. Both use extensive security libraries and frameworks,  such as Java’s Java Cryptography Extension (JCE) and C#’s .NET Cryptography Library,.

With that said, they also do some things differently. 

Java uses a sandboxing approach and its own Security Manager. That means that untrusted code is confined within a controlled environment and can’t access sensitive resources without authorization. Also, Java utilizes bytecode verification, which ensures only trusted code can get executed. 

C# and the .NET framework offer a wealth of security libraries themselves. Frameworks such as the Windows Identity Foundation (WIF) significantly enhance identity management and authentication capabilities. 

Wrap up

C# and Java are both powerful programming languages with their own capabilities, strengths and weaknesses. Both languages offer a rich set of libraries to use, depending on your specific needs. Both have long, rich histories and are backed by large corporations, making them safe choices for long-term projects.

Java, thanks to its mature ecosystem and performance optimisations, used to be the go-to pick for large-scale enterprise systems. However, with the open-sourcing of .NET Core, the transition to .NET 8 and beyond, and the rise of cloud-based solutions like Azure, C# has also become more suitable for large-scale enterprise use. 

C# might also offer faster development cycles for certain types of applications, especially if you’re utilizing Microsoft’s ecosystem. In terms of cost, Java is free to use, especially for open-source projects, giving it the edge in that regard. 

Ultimately, the C# vs Java choice for your project should be based on specific needs, goals, and context. Hopefully, knowing what each of the two excels at will help you make an informed decision. 


A reader who loves writing, a marketer who loves tech, a nerd who loves sports. Dilyan, our resident writer, half-jokes that his days are filled with everything you can think of - except free time. He joined our team several years into his copywriting career - and he seems to feel at home here. Because, as he puts it, “there’s always cake at the office”.  If he doesn’t have his nose buried in a book, you can typically find Dilyan writing his latest piece, tinkering with his PC, or off swimming/cycling somewhere.