After C#, Python, JavaScript, SQL, HTML, CSS, and Go, I arrived at Java. And it was a completely different experience. If Go taught me to respect hardware and think about resources, Java taught me to think about architecture. About how to build large systems that live for decades, evolve, and don't collapse under their own weight. Java has existed since 1995 and still remains the foundation of the global IT industry. And that's no coincidence.

In this post, I'm sharing only personal observations. No attempt to claim Java is the "best" or the "worst" language. Just an honest breakdown of what Java taught me, where it proved indispensable, and where it made me miss the conciseness of Go or the speed of Python. And why I believe writing Java off in the era of AI and microservices is a serious mistake.

Why Java Came Next

After Go, I wanted to understand a language built for large systems. Go is the language of infrastructure — it shines in microservices and CLI tools. But Java is the language of enterprise. Banks, telecom, insurance, large corporate systems — all of this runs on Java. And that's no coincidence either. It was a deliberate choice by engineers who needed maturity, reliability, and a huge ecosystem.

There was a second motive too. After Go, where concurrency is built on lightweight goroutines, I wanted to understand how classic threads work, how the JVM (Java Virtual Machine) is built, and why it remains one of the most optimized virtual machines in the world. And also — how Java adapts to the modern world: virtual threads, GraalVM, integration with AI.

My conviction: C# teaches discipline, Python teaches speed, JavaScript teaches patience, SQL teaches thinking in data, HTML & CSS teach empathy for the user, Go teaches respect for resources, and Java teaches architectural thinking. This language forces you to think about the system as a whole, not just about a single function.

What Exactly I Studied

OOP Classes, inheritance, polymorphism, encapsulation, abstraction — the four pillars Java stands on.
JVM Java Virtual Machine — bytecode, JIT compilation, runtime optimization, cross-platform execution.
Threads Classic threads, ExecutorService, CompletableFuture, and virtual threads (Project Loom).
Garbage Collection G1, ZGC, Shenandoah — modern collectors with pauses under a millisecond.
Spring Spring Boot, Spring Cloud, Spring Data — the standard for enterprise development in Java.
Exceptions Checked and unchecked exceptions. try-catch-finally. Discipline in error handling.

Strengths of Java

1. Strict Typing and Reliability

Java is a strictly typed language. Every variable, every parameter, every return value has a clear type. The compiler verifies this at build time. This means many errors are caught before the program runs, not in production.

After JavaScript with its dynamic typing, this feels like a breath of fresh air. You know for sure that if the code compiled, the types are consistent. And that's critical for large projects where dozens of developers work on the same codebase.

2. Cross-Platform via the JVM

"Write once, run anywhere." This has been Java's slogan from the start. And it's still true. Java code compiles not into machine code, but into bytecode, which runs on the JVM. This means the same `.jar` file can run on Windows, Linux, macOS, Android — anywhere there's a JVM.

The JVM is a true engineering masterpiece. It doesn't just execute bytecode, it adapts to your code. The JIT compiler analyzes hot paths and optimizes them on the fly. As a result, a Java application can run faster than an equivalent C++ one in certain scenarios.

3. Virtual Threads (Project Loom)

For a long time, Java was criticized for "heavy" threads: every Java thread was an OS thread, and that's expensive. But in Java 21, virtual threads arrived (Project Loom). These are lightweight threads managed by the JVM, not the operating system.

You can run millions of virtual threads at the same time, and each one is blocking — that is, written in the familiar synchronous style. This radically simplifies building high-load applications: you don't think about reactive chains and callbacks like in Node.js; you just write ordinary code.

4. A Massive Ecosystem

Over 30 years, Java has grown the most mature ecosystem in the programming world. Libraries, frameworks, tools, documentation — all of this is abundant. Spring, Hibernate, Apache Commons, Maven, Gradle — these tools are battle-tested and reliable.

This means practically any task has already been solved by someone. You don't have to reinvent the wheel. For AI there's Deeplearning4j, Tribuo, ONNX Runtime. For microservices — Spring Cloud, Quarkus, Micronaut. For Big Data — Apache Hadoop, Spark, Kafka.

5. Modern Garbage Collection

Java doesn't stand still. If in the past the garbage collector could freeze an application for seconds, today there's ZGC and Shenandoah — collectors with pauses under a millisecond, even on terabyte heaps.

The GraalVM virtual machine can compile Java into native code, giving instant startup and minimal memory usage. This opens Java's path into serverless and CLI tools, where it used to be inconvenient.

6. Java and AI in 2026

Java has long been more than just enterprise. In 2026, Java is actively used in AI: the LangChain4j framework for LLMs, Spring AI for integrating AI into applications, Deeplearning4j for neural networks. Spring AI lets you build RAG systems, work with vector databases and LLMs without leaving for Python.

Large companies increasingly choose Java for AI in production because it provides what Python lacks: strict typing, reliability, scalability, and a unified stack with the rest of the infrastructure.

Weaknesses of Java

1. Verbosity

Java is famous for its verbosity. What takes three lines in Python can take ten in Java. Getters, setters, constructors, annotations — all of it takes time and space. Lombok, Records (Java 14+), and Kotlin partially solve the problem, but the feeling of "too many letters" remains.

2. Slow Startup

The classic JVM takes a long time to start. Initially, the application runs slowly until the JIT compiler warms up the hot paths. For microservices with frequent restarts, this is a noticeable problem.

GraalVM Native Image and projects like Quarkus and Micronaut solve this — they compile Java into native code with instant startup. But this requires additional setup and sometimes limits the use of reflection and dynamic capabilities.

3. Memory Consumption

Java is gluttonous compared to Go or Rust. Every object has a header, every thread allocates a stack, the JVM itself requires memory. If a Go service can run in 20 MB, a Java service with Spring Boot easily consumes 300–500 MB.

For containers and serverless, this is critical. Although modern collectors and GraalVM help, the gap is still noticeable.

4. Learning Complexity

Java is not for beginners. You need to understand OOP, types, exceptions, generics, collections, threads, and the JVM. The learning curve is steep. And if you don't understand how the JVM works, you won't be able to optimize a Java application.

5. Legacy Code

The flip side of 30 years of history is a huge amount of outdated code. Legacy projects on Java 6 or Java 8 still run in banks and government agencies. And maintaining them is painful.

Sometimes a Java developer spends most of their time on migration and refactoring of old code rather than writing new code. This isn't a language problem, but it is the reality of the market.

6. Competition from Kotlin

Inside the JVM world, Java competes with Kotlin — a more concise and modern language that became the official one for Android. Many new JVM projects are written in Kotlin, while Java remains for legacy and enterprise.

Bottom line on weaknesses: Java's flaws are the price of cross-platform capability, maturity, and reliability. The language was created for enterprise and still serves it faithfully. It evolves, but it can't escape the legacy of 30 years of history.

How Did Java Shape My Thinking?

After seven languages, Java gave me an eighth perspective on development. Here's what I took away:

  • Architecture matters more than code. Think about the system, not just the function.
  • Types are documentation that the compiler verifies.
  • The JVM is an engineering marvel. Understanding it means understanding performance.
  • Ecosystem maturity matters more than a language's trendiness.
  • Microservices and AI on Java are real — it's not just Python and Go.

And most importantly: Java taught me to think decades ahead. Code you write today may live for another 20 years. And that changes your approach to design.

Verdict: Is Java Worth Learning in 2026?

Unequivocally — yes. And not as a "replacement" for Go or Python, but as a foundation for large systems. Java won't die: too much business depends on it. And it's actively evolving: virtual threads, GraalVM, integration with AI.

For those building a career in enterprise — Java is essential. For those working with microservices — Java (especially Quarkus and Spring Boot) delivers power and maturity. For those who want to enter AI in production — Java is becoming an increasingly serious choice.

For me personally, Java became a tool for understanding architecture. C# is the brain of the server, Python is the power of data and AI, JavaScript is the language of interaction, SQL is the foundation of data, HTML & CSS are the user's eyes, Go is the skeleton of the cloud, and Java is the backbone of enterprise. And in 2026, that backbone has only gotten stronger: virtual threads, GraalVM, and AI frameworks have made Java more modern than many people think.

So learn Java — but learn it correctly. Don't write in it like you would in Go. Embrace its philosophy: strictness, explicitness, architectural thinking. And then you'll understand why banks, telecom, and the largest systems in the world still choose Java.