Real World Lean Java Practices, Patterns, Hacks, and Workarounds

This interreactive session is about practical, no-nonsense coding. We'll explore lean Java 21+ practices and patterns that eliminate bloat and hacks that increase productivity. We will start with structuring and organizing backend monoliths and microservices, cover testing, then move on to decoupling, abstractions, Data Oriented Programming, automation with pure Java, and the impact of LLM assistants on design and code structure.

Presented by Adam Bien (Java Champion & Architect ) at JavaOne 2025 (CA, March 2025).

Tags: #Java #JavaOne

SES1112

[mobbs]

Video chapters would be much appreciated, dear folks.

[ooijaz]

Amazing talk! I moved to go(lang) for my personal projects seeking simplicity (doing spring in day to day job) but after this talk I think I will give Java another try.
We need more people like Adam in the community - understanding how things works under the hood is 100x times harder with todays standard tooling with tons of dependencies which hurts new developers and slows down everyone.

[aturan-foqt]

Thank you, Adam! You have been doing great things for decades 👍

[MaximusPower]

These are nice pragmatic approaches! Great Session as food for thought!

I can take these considerations always having in mind the size and purpose of the application. The advice of "Cache is Evil" because of the downside of inconsistency simply can't work in any slightly bigger application.

In a big platform with millions of requests, say 5k TPS. There's no way to fetch data from the disk for every request we receive.
It not possible to afford the addition of the I/O latency in the name of consistency.

If you always keep in mind the pragmatism of these approaches strictly based on this application context, then this session is valuable.

[yatsuk]

Would start a new project using Jakarta EE application server or Spring Boot is only the way to go?

[jesper]

I wish the talk was a bit longer, the presentation felt a bit stressed and some things were quickly mentioned before moving on to the next thing.

[riccardon-gj]

Whenever unit testing is skipped you'll find a badly designed class. You don't need 100% coverage but you need a place where to test a bug fix easily if you rely on system tests only it becomes cumbersome

[rezah]

ok, i watched 5 minutes and i still dont know what he is talking about and i didnt here anything about the topics in the title

if you want to improve the image of java you have to do better PR, this is complete nonsense, just cover the topics with real world examples

[pranaytripathi]

Can we get a link to the uploaded code or something ?

[KangoV]

Nice talk, but field level injection is evil (imo).

[riccardon-gj]

Jpa is too much sometimes I agree simply jdbc or jetbrains exposed ... Something simple gives better performance

[rydmerlin]

Reminds me of how people were less vulnerable on log4j 1 vs 2.

[sjzara]

Rust and C are not faster for applications that do anything substantial with memory and especially with multithreading. Speculative compiling means Java can be much faster when forms of inheritance are involved.

[peteabc]

Java actually got some breaking changes, like removal of the finalizers, some packages were removed/renamed etc. I consider C to be more stable (but it's not suitable for web dev). But it's not as bad as php where a major lang release usually means you must review and refactor your whole code base.

[Maximus]

Not a java developer myself but that third table (Mb) scares me, CSharp is at 3.86 and Java at 6 ? That is terrible. ...If Rust is a "bit" faster (its order of magnitudes faster), harder to learn and has very few develoeprs, isn't that a good thing for developers? Maybe he is talking from the employer's point of view.

[luisdanielmesa]

I agree on 90% - 95%
Everything is automated from the start, all environments are the same and code coverage is at 100% from the beginning for simple CRUD services. After you start adding stuff you just have to maintain it or be happy with whatever coverage you choose.
The services are 30MB and start in milliseconds.