Comparing Rust and Java

A Journey of Discovery for a Java Developer

Introduction

As an experienced Java/Kotlin developer with a background in Python and C#, I’ve primarily worked with Spring Boot for years. You could call me a Spring developer. However, recently, I’ve felt like I’ve hit a plateau in my growth and wanted to challenge myself by learning a new language—something fundamentally different from what I already know. That’s how I embarked on my journey to learn Rust.

In this article, I’ll share my experiences transitioning from Java to Rust and compare these languages from the perspective of a seasoned Java developer. Along the way, I’ll discuss the challenges, benefits, and how Rust made me rethink some key aspects of software development.

Learning Rust: A Different Journey

A Decade of Familiarity

Learning new languages has always been relatively easy for me. For example:

• Kotlin: Since it’s very similar to Java, I picked it up in a week and was confident enough to write production code right away.
• Lua: While it wasn’t difficult, the challenge was more about adapting to a new paradigm after not learning anything new for a while.
• Python: It was also straightforward since I had prior experience with Java and C#. I quickly became proficient enough to build robust services.

However, Rust was a completely different story. I’d heard of Rust years ago, but it wasn’t until a few months ago that I committed to learning it seriously. The journey has been unique and far more challenging than any language I’ve learned in the past.

Rust’s Ownership Model: A Paradigm Shift

One of the most challenging and eye-opening aspects of Rust is its ownership model and the concept of lifetimes. Unlike my previous experience with garbage-collected (GC) languages like Java, Kotlin, and Python, or manual memory management in C, Rust introduces a middle ground:

• With GC-based languages, memory management is often an afterthought for developers.
• In C, memory management is manual and error-prone (e.g., segmentation faults due to improper allocation).
• Rust enforces memory safety at compile time, thanks to its ownership model.

Initially, ownership and lifetimes were hard to grasp. But over time, I began to appreciate the elegance of this approach. It also made me question the use of “zero-GC” in Java for low-latency systems. If developers go out of their way to avoid Java’s GC, why not use Rust or C++ instead? Rust’s memory management feels like a natural fit for such scenarios.

Error Handling: Rethinking Exceptions

Coming from Java, I was used to traditional exception handling with try/catch blocks. Even C# and Python provide similar mechanisms. However, Rust takes a very different approach:

• Rust avoids exceptions altogether. Instead, it uses enums like Result and Option to handle errors.
• At first, this felt unnatural. I kept looking for ways to “throw” errors. But Rust encourages you to handle all possible errors explicitly, eliminating the risks of uncaught exceptions.

This has fundamentally changed the way I think about error handling in Java. Throwing exceptions that crash the program feels similar to Rust’s panic!, but Rust makes it harder to reach that point. I now try to avoid throwing exceptions in Java wherever possible.

Data Structures: A Learning Curve

Linked Lists: A Simple Yet Eye-Opening Case

In Java and Python, implementing a linked list is straightforward. In Rust, it’s not as easy due to the ownership model:

• You need to wrap the next pointer in an Option<Box<Node>> to satisfy Rust’s ownership rules.
• Accessing or updating the next pointer requires un/wrapping and un/boxing, leading to more lines of code.

While this complexity can be frustrating, it forced me to better understand how memory is managed under the hood—a valuable learning experience.

Ecosystem Comparison: Java vs. Rust

Web Development

As someone who has used Spring Boot extensively, I’m accustomed to a rich ecosystem with features like dependency injection, built-in metrics, and seamless integration with databases. Rust’s web frameworks, like Actix and Warp, are powerful but still lack the level of maturity and user-friendliness of Spring Boot.

However, I was pleasantly surprised by Rust’s async ecosystem, particularly Tokio. It’s easier to work with than Java’s Project Reactor or Spring WebFlux for asynchronous programming.

Personal Reflections: Why I’m Sticking with Rust

Despite its challenges, I’m drawn to Rust because it offers a fresh perspective. It’s a language that makes you think differently about memory, safety, and error handling. While I still write a lot of Java code professionally, learning Rust has been a rewarding experience that has expanded my horizons.

Rust isn’t just a tool for system programming; it’s a language that encourages better practices, even in other languages like Java.

Conclusion

Rust and Java cater to different domains, but they both have their strengths. Java excels in enterprise environments with its mature ecosystem, while Rust shines in areas where performance and safety are critical. For developers looking to grow, Rust provides a refreshing and challenging experience that will undoubtedly make you a better programmer, even if you continue to use Java professionally.

Whether you’re a seasoned developer or just starting out, I encourage you to give Rust a try. It’s not just a language; it’s a mindset.