Java for backend vs frontend: what to choose in 2024?

Java for backend vs frontend: pros and cons — a battle of titans

When it comes to Java, most developers immediately imagine powerful server applications, enterprise systems, and banking transactions. But few people know that Java can also work on the client side — in the browser or on the desktop. And this is where it gets interesting: is it worth using one language for two completely different worlds? Let's figure out what Java actually offers for backend and frontend, where its strength lies, and where its weakness is.

Why does Java still rule in backend?

Java is not just a language, it's an ecosystem. It conquered backend development thanks to its reliability, performance, and incredible scalability. If you write server-side code in Java, you get:

\n
• Stability and predictability. Code written in Java runs for years without failures. This is not a case where a library update breaks the entire application.
\n
• Huge community. Millions of developers, thousands of libraries, frameworks, and tools. Any problem has already been solved by someone.
\n
• Performance. Thanks to JIT compilation and modern garbage collectors, Java can handle enormous loads.
\n

But the main thing is the Spring Framework. It's practically the de facto standard for enterprise development. Spring Boot allows you to launch a full-fledged REST API in 10 minutes. Here's what a simple backend in Java looks like:

import org.springframework.boot.SpringApplication;\nimport org.springframework.boot.autoconfigure.SpringBootApplication;\nimport org.springframework.web.bind.annotation.GetMapping;\nimport org.springframework.web.bind.annotation.RestController;\n\n@SpringBootApplication\n@RestController\npublic class BackendApp {\n\n    public static void main(String[] args) {\n        SpringApplication.run(BackendApp.class, args);\n    }\n\n    @GetMapping("/hello")\n    public String sayHello() {\n        return "Hello, world! This is a backend in Java!";\n    }\n}

This code is minimal, but it already handles HTTP requests, is ready for scaling, and integrates with databases. This is why Java is loved in backend.

What about frontend? Java on the client — myth or reality?

When people say "Java frontend," many are surprised. But Java can indeed work in the browser — through applets (which are almost dead), through GWT (Google Web Toolkit), and modern frameworks like Vaadin or JSF. However, there is a catch.

Java on the frontend is not about "writing a script and inserting it into HTML." It's about generating UI on the server or compiling Java code into JavaScript. For example, Vaadin allows you to write interfaces entirely in Java, and the framework renders HTML+JS itself. It looks like this:

import com.vaadin.flow.component.button.Button;\nimport com.vaadin.flow.component.notification.Notification;\nimport com.vaadin.flow.component.orderedlayout.VerticalLayout;\nimport com.vaadin.flow.router.Route;\n\n@Route("")\npublic class MainView extends VerticalLayout {\n\n    public MainView() {\n        Button button = new Button("Click me!",\n            event -> Notification.show("Hello from Java frontend!"));\n        add(button);\n    }\n}

Is it beautiful? Yes. Convenient for a Java developer? Absolutely. But there's a catch — it's not native frontend. You won't be able to easily integrate with modern JavaScript libraries, and performance may suffer on complex interfaces.

Pros of Java for backend: why it's the best choice

If you are building a serious project that should run for years, Java for backend is almost a sure bet. Here are the specific pros:

\n
• Multithreading out of the box. Java has excellent support for multithreading, which is critical for high-load systems.
\n