[javaone 2025] opening keynote

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Chad Arimura

Started with history including pictures from the first JavaOne in 1996 and what Duke looked like then. Fast forward to present day. Java 24 launched this morning

Scott McNealty (retired but was here for the beginning) and Colt McNealy (Scott’s son)

Scott’s reminisced about the start of Java. Were originally planning on making a clicker. Never did but did better. Talked about licensing stuff to companies for a fee. Virtualization; creating a mess.

In the background was Fortune magazine’s JavaMan cartoon of Scott McNealy needing to stop Bill Gates from dominating the corporate universe.

Colt took AP computer science, went to Stamford and then got a real job. Real word harder than college where everything runs on one laptop. Created open source Lighthouse to get insights into threads, etc

Georges Saab

  • 94 of Fortune 100 run Java
  • Small companies use Java too
  • ex: Uber, Netflix, LinkedIn
  • 6 billion java cars deployed each year – ex: smartphones have two Java parts, credit cards, RFID cards, car
  • 15 releases under 6 month cadeence (since Java 10)

Mark Cavage

  • “crazy Mark” to disambiguate which Mark (vs Mark Reinhold). “Crazy” because proposed six month cadence
  • Now at Docker
  • 8M Java developers on Docker
  • Can run LLMs natively in Docker: docker model run ai/llama3.2:1b

Georges Saab

  • Not every change gets a JEP
  • Read release notes
  • Performance

Mingmin Chen (Head of Uber’s real time search platform)

  • Asked how many people used Uber in last 30 days. It was almost everyone.
  • Use Kafka, Flink, Pinot, judi, spark, presto, open search
  • Generational ZGC to reduce memory usage. Also reduced CPU

Georges Saab

AI

  • code generation/assistance
  • model integration for business apps (langchain4j)
  • model training (panama, valhalla, babylon)

New learners

  • simple source files
  • instance main methods
  • single/multi file source code launcher
  • script ready shebang upport

Missed name but someone from College Board and also Heather Stevens

  • AP Computer Science A being revised in Fall 2025 from Java 8
  • Encouraging teachers each year to use latest version of java
  • Exam has used Java for 0ver 20 years [I took it when Pascal and C++)
  • A third of schools with one AP class have Computer Science A

Mark Reinhold

  • Developer vs steward
  • Reading is more important than writing
  • Simplicity matters
  • Java should be one language with the same meaning everywhere
  • Java has never been about write once and throwaway code. [that’s what vibe coding is I think?]
  • “first do no harm”
  • Compatibility – source, binary, behavioral, migration, intellectual (build on existing knowledge)
  • Project Amber “paving the on ramp”.

JEPS 494 and 495 with more to come

  • Showed evolving the classic Hello World to use an instance main, removing the args, removing class declaration, import so can write println(). Final form is
1
2
3
void main() {
   println("Hello World!");
}
  • import module java.base; to import everything in module in one shot
  • chmod +x fileName; ./fileName to run

Garbage Collection

  • Compared garbage collectors. ZGC from Java 15 is extremely low latency..
  • In Java 17, got to sub millisecond pause times.
  • ZGC doesn’t scale well . Fixed in Java 21 by making generational
  • Still need multiple garbage collectors because GC uses a lot of memory.
  • Java 24 – improved latency in Parallel an G1 garbage collectors

Paul Bakker (Netflix)

  • Use GraphQL, Spring Boot, Kafka, gRPC, cassandra, etc
  • Had client timeouts from pause times. Switched to ZGC and saw no pause times so clients have less errors

Mark Reinhold

Project Leyden

  • improve startup time
  • Move work earlier or later
  • Goal is to avoid new contrainst on existing code, without changing spec and without making Java less dynamic
  • Instead use training runs
  • Training: java -XX:AOTMode=record -XX:AOTConfiguration-app.aotconf…
  • Assembly: java -XX:AOTMode=create -XX:AOTConfiguration-app.aotconf.-XX:AOTCache=-app.aot ….
  • Execution: java -XX:AOTCache=-app.aot ….
  • Can do a lot of work up front,. Too long to list. Ex: link classe (in Java 24) and more in future versions of Java
  • Took about 30% of the original time before Leyden

Native libraries

  • hard to use JNI by design
  • Useful for crypto, ML, etc
  • Project Panama add Foreign Function and Memory API. Use jextract to automatically generate bindings rom the C/C++ header file.

Paul Sandoz

  • Function is code and weights
  • Training computes the weights
  • ONNX – open neural network exchange for ML. Includes interoperable format for ML models and runtime for executing them
  • Use Panama and jextract to bind to onnx.h file

Mark Reinhold

More pain points

  • Quantum computing will break RSA. Preparing with Key encapsulation, key derivation, quantum resistant mechanism/algorithms. Will eventually back port to past LTS releases.
  • The stream API isn’t fully extensible. Java 24 stream gatherers
  • My favorite bytecode library breaks on Java 21 – “stop using it” . Class file API
  • Writing raw HTML in JavaDoc is tedious. Now can use markdown.
  • You aren’t delivering new features quickly enough – integrity by default. Need to be able to refactor JDK internals. Deprecate/remove things not used

Bruno Borges and Mark Heckler (Microsoft)

  • VS Code, (3 million monthly downloads) GitHub, Azure (95% of Fortune 500 customers)
  • AI agent – create a plan, retrieve context, perform an action
  • Nice demo of Copilot chat in VS Code. Also showed Codespaces
  • Microsoft has 2.5 million JMVs running internally. Includes Minecraft, Bing, etc
  • Minecraft uses Java 21

Chad Arimura

  • dev.java – tutorials for latest features. Meant for professionals
  • learn.java – new. For teachers and students

My take

I like that they covered a lot and quickly. Some things were interesting like the AP changes but only needed a few minutes to cover so it was great that is what they got. While the language parts weren’t new to me, it was well covered. Also nice Mark threw in a few cat pictures. I hadn’t heard of Project Leyden or GRPC along with some of the new features. And I wasn’t familiar with the native binding changes. Nice to learn a bunch of new stuff. It was nice to see a few demos as well

[javaone 2025] table of contents

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Welcome to my live blog (probably) here from JavaOne. The probably is because I hurt my wrist a week ago. This is the most typing I’ve done on a laptop since so will see how it works out! [typing is going fine on a laptop. Not ready to type fast on the iPad keyboard though. Luckily there is power so I’m able to recharge the laptop]

The day started with Duke welcoming attendees. Hi Duke! (Check out his badge/job title). I made a joke about hoping they didn’t charge Duke for the badge. The Oracle employee said Duke is the host!

Check in was fast and there was a coat check. Appreciated not having to carry around a coat all day!

Tuesday

Wednesday

why a FIRST robotics WFFA essay means so much

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FIRST robotics competition team 694 nominated me as their Woodie Flowers Award candidate this year. (I won the Woodie Flowers Finalist Award in 2012 at the NYC regional. That was a long time ago so the essay was completely different).

This award is to celebrate effective communication in the art and science of engineering and design.” The students write an essay about the mentor they nominate. I encourage all teams to submit an essay. Both because “you have to be in it to win it” and also because it is a great way to show your mentor that you appreciate them.

And it definitely worked out that way. I LOVED reading the essay the students submitted today. I got to see the Google doc a few hours before submission. Which included three sections

Part 1: Bullet notes from students brainstorming

I enjoyed reading this part because it let me see what the students were thinking. And also the ideas they had that didn’t make it into the essay due to space constraints. For example, they included “nighttime rehearsals.” I think they were right not to include this in the final essay. But it was still nice to see those practice sessions were appreciated!

Part 2: Quotes from student members about me

This year, the students included some quotes in the essays. Seeing the quotes they came up with draw from was a lot of fun. Some were things I would have recollected. Others were things I didn’t think anything of at the time. For example:

At FLR after 694 won the Impact Award, she made sure to give due credit to PulseCrew and the whole team for making it possible -> makes everyone feel included and part of the team community 

I absolutely did this. What I didn’t do is reflect on the impact. Seeing it written down gives me a happy feeling because it shows I included people without thinking about it. And inclusion is one of the FIRST core values, so that’s great!

Part 3: The Essay

As I started reading the essay I immediately smiled. What the students don’t know is that I got that bow in 2018 or so because the girls on the team that year ordered bows as swag. When one of them handed me a bow and asked if I would wear it at competition. I was hesitant. I’m not a frilly/bow person. I said I would wear it to a Saturday meeting and then decide. I did always put my hair up in a half ponytail and the bow felt this same. So I said yes. Then at the NYC regional, a volunteer was looking for me and described me as “the volunteer with the big red bow.” That beats the pants off “the medium height lady with the brown hair.” So the bow became a thing that I wear now. I like that the girls on the team years ago had a transitive impact on a student this year.

A bright red bow, used to mitigate the missing presence of red from StuyPulse’s t-shirt, which was caused by the absolute necessity of wearing the FIRST Volunteer t-shirt instead as the NYC FRC Volunteer Coordinator, seemed to shine and speak to me from the back of Jeanne’s head. 

There was so much in the essay that I enjoyed reading. This passage resonated with me because *I* came to the FIRST community from the outside. (I’m not an alum or a teacher or a parent. I found out about FIRST from a public demo 694 around 2008. They told me the event was free. I went and then started volunteering. Then in 2010, Java was a choice of programming language and I started as a mentor.) When I won the Woodie Flowers Finalist Award in 2012, one of the students (Alex) in software asked me “do you feel like a part of the FIRST community.” That was the exact moment where I felt like I did!

Wearing that pink tiara, I felt like a part of the robotics community; watching Jeanne speedwalk throughout the venue keeping order, I felt in awe of the FIRST community, recognizing that there is so much to do, so much dedication and opportunity. 

I like that they included things that were important to me. While I don’t know about magic :), I am proud of the fact that they’ve never seen me code for the robot. [I have done work there and I did some writing towards my book in the lab. So they have seen me code. But that’s not robot code]

having never touched the keyboard and instead watched us code while speaking words of advice or magic 

Then there were memories from the past. This was a quote from something that happened freshman year for a student who is now a senior. Granted I’ve given other students similar advice. But it’s cool that this student remembers it!


She made me hold paper when I first tried out for impact. ‘If you’re holding something, you can’t put your hands in your pockets and you can’t fidget 

And then the ending was great. I’ve always had mixed feelings about women in tech stuff. Like when I got asked to be on a panel, my thought process along the lines of “I wish gender in tech didn’t matter”, “but it does and girls/women need role models”, “I guess I should”…. This sentence resonates for me because I didn’t talk about being a female in STEM. I was me; who was a role model by happening to be female while mentoring on software and awards and just being there.


At competitions I now wear a red bow in my hair, proud to be a girl in STEM and happy to be a part of this FIRST community, with a mentor like Jeanne. 

Finally

Thank you to everyone who was involved in the writing of this essay. It means so much to me. The time you spent on writing was very much worth it.