Java in Japan: A Journey of Community, Culture, and Global Integration (JavaOne 2025)

© 2025 NTT DATA Group Japan Corporation
Java in Japan: A Journey of Community,
Culture, and Global Integration
Mar. 19th, 2025
NTT DATA Group Corporation
Koichi Sakata

© 2025 NTT DATA Group Japan Corporation 2
About Me
Koichi SAKATA (阪田浩一)
Java Champion
OpenJDK Committer
jyukutyo

Communities matter

Java User Groups
4

Java User Groups (JUGs)
• Volunteer organizations that distribute knowledge
• Regular meet-ups
• Known as JUGs

Global Java User Groups
• 344 JUGs in the world
• 291 Active Groups
https://dev.java/community/jugs/

Japan's Java User Groups
Japan Java User Group
(JJUG)
KanJava
https://dev.java/community/jugs/

• Population: 124 million
• Language: Japanese
• Capital: Tokyo
• Currency: Japanese Yen (JPY)
Japan

• Island Country: Comprised of 4 main islands
• Honshu, Hokkaido, Kyushu, Shikoku
• Major Cities: Osaka, Kyoto, Yokohama
• Famous for: Technology, traditional culture, cuisine
(e.g. sushi, ramen)
Japan
Joint Research Centre, ECHO, European Commission, CC BY 4.0, via Wikimedia Commons

Java in Japan
• Java has been a popular programming language in Japan since
the early 2000s.
• It remains widely used, especially in enterprise system
development.
• Contributions were made from Japan to internationalization
features in JDK 1.1.
Duke おにぎり, Java Day Tokyo 2015 Java 20周年記念イベント by Yuichi Sakuraba (CC BY-NC 2.0)

Java in Japan
• Due to its popularity, JavaOne Japan was once held.
General Session, JavaOne Tokyo 2005 by Yuichi Sakuraba (CC BY-NC 2.0) JK1-01 Strategy Keynote, JavaOne Tokyo 2012 by Yuichi Sakuraba (CC BY-NC 2.0)

Acitive JUGs in Japan
• Japan Java User Group (JJUG)
• Place: Tokyo
• Members: 12,000
• Meet-up: Monthly
• URL: https://www.java-users.jp/
• KanJava
• Place: Osaka
• Members: 1,100
• Meet-up: Bimonthly
• URL: https://kanjava.connpass.com/

Java Conference and JUG Meet-up
Conferences JUG Meet-ups
Frequency Once a year Once every 1-2 months
Attendees Hundreds to thousand Dozens
Fee Type Paid Free

2009
• The only JUG was JJUG
• I lived in Osaka
• Tokyo and Osaka are 500 km apart
• I wanted a Java community in my city
• To discuss technology and have fun

Creating our own JUG
• Created a new JUG with friends
• KanJava
• Organized events and announced them
on a website like Meetup.com

Holding Events
• A dozen attendees at first few meetings
• Over half of them were people I knew
• Attendance increased with each event

KanJava
• Kan means Kansai area in Japan
- West side including Osaka, Kyoto and Kobe
• 70 meetings held
• Sometimes speakers
from other countries as well
T.Kambayashi, CC BY-SA 3.0, via Wikimedia Commons

Persistence Pays Off
• Recognized not only in Osaka but throughout Japan by
continuing for many years
• Speakers came from various places, including Tokyo

Running a JUG
• Starting a JUG has definitely changed my life
• However, running a JUG is not always fun

Organizing Meet-ups is Not Easy
• Securing a venue
• Finding speakers
• Few speaker candidates
• Promoting the meet-up and attracting attendees
• Managing the event on the day
• Ordering pizza (in the right amount!)
• Dealing with occasional unwarranted complaints

Benefits for Organizers
• Unique opportunities for organizers
• Easier access to speakers
• Interaction with accomplished individuals
• These interactions have a significant impact

The Ongoing Legacy of KanJava
• Founded KanJava and served as leader for 10 years.
• Stepped down as leader when I moved from Osaka to Tokyo
for a career change.
• Leadership was successfully passed on, and KanJava continues
today.
• KanJava remains an essential community space due to its
long-term impact and value.

Is there a JUG in your city?
• If yes, join it!
• If possible, help with the organization
• Consider becoming a speaker
• If no, you can start one yourself!

Benefits of Becoming a Speaker
• Have you ever tried speaking at a meet-up?
• Speaking can be challenging, but it offers incredible
experiences:
• Easier to connect with attendees
• You learn the most about your own topic
• Improve various skills
• Take the leap and become a speaker!

What I Learned Through JUGs
• Learned about the JavaOne conference held in the US
• Discovered the title of Java Champion

Attending JavaOne
• Attended JavaOne (Oracle Code One) since 2015
• First JavaOne at age 36!
• Witnessed Japanese speakers presenting in English
JavaOne 2015 San Francisco by Yuichi Sakuraba (CC BY-NC 2.0)

Impact of JavaOne
• Shocking experience for a Japanese person
• Thought only those with long-term study abroad or raised in English-
speaking countries could present in English
• Seemed like Jedi training from Star Wars, impossible for ordinary
people like me

Language Distance Between Japanese and English
• FSI Language Difficulty Ranking[1]: Time required for native
English speakers to learn different languages
• Category I Languages: 24-30 weeks (552-690 class hours)
• Category IV Languages: 88 weeks (2200 class hours)
• Japanese: Super-hard language (Category IV)
• And vice versa: Similar difficulty for Japanese speakers to learn
English
[1] https://www.state.gov/foreign-service-institute/foreign-language-training

Japanese English Education
• Not effective in schools
• Focus on translating Japanese to English
• Very little practice in speaking and listening
• My first conversation with a person from abroad at 35 years old
• Pronunciation based on Katakana
• L and R sounds

I Might Be Able to Do It Too
• Many have overcome these high hurdles
• The thought that I might be able to do it too arose
• And now, I am achieving it!

Java Champions
3

Meeting a Java Champion
• One of the speakers at KanJava was a Java Champion
• At that time, he was the only Java Champion in Japan
JJUG CCC June 2024 by Jim Grisanzio (CC BY-NC-SA 2.0)

Java Champions
• A program sponsored by Oracle
• Unique group of skilled Java technologists and community
leaders
• Leaders, influencers, and enablers who help grow the Java
community
• Active in Java projects, JUGs, conferences, authoring, teaching,
and fostering inclusive participation
• Technical and community luminaries, credible and dedicated

2017
• Java experts from various countries came to Japan
• Relaxing unconference at a hot spring
• Several Java Champions attended
• Named JOnsen, a 3-day, 2-night event
• Possible influences: interest in Japan, Java usage, and active
JUG activities

Onsen (Hot Springs)
• Natural hot springs found throughout Japan
• Traditionally used for bathing and relaxation
• Rich in minerals and believed to have healing properties
• Popular tourist destinations
• Examples: Hakone, Beppu, Kusatsu

Participation in JOnsen
• Invited to participate as a JUG leader
• Attended every year since 2017, except during the COVID-19
pandemic
JOnsen 2017 by Yuichi Sakuraba (CC BY-NC 2.0) JOnsen 2017 by Yuichi Sakuraba (CC BY-NC 2.0)

Becoming a Java Champion
• JOnsen helped many Java Champions get to know me
• To become a Java Champion, one must be nominated and
voted in by existing Java Champions
• My activities as a JUG leader, author, and speaker were
recognized

Activities of Java Champions in Japan
• Several Japanese Java Champions actively contribute within
Japan.
• Key activities:
• Speaking at events
• Writing for media outlets
• The title "Java Champion" is relatively well-known in Japan due
to these efforts.

Integration into the Global Community
• JOnsen was a fortunate start
• JJUG leaders connected the Japanese Java community to the
global community
• Japan's long-term use of Java in applications is a significant
contribution

JJUG's Role in the JCP
• JJUG is an Executive Committee (EC) Member of the JCP.
• What is the JCP?
• The Java Community Process (JCP) standardizes Java specifications.
• Ensures high-quality specs via a consensus-based approach.
• Requires Reference Implementations (RI) and Technology Compatibility
Kits (TCK).
https://jcp.org/en/participation/committee

JJUG's Role in the JCP
• JJUG is an Executive Committee (EC) Member of the JCP.
• What is the JCP?
• The Java Community Process (JCP) standardizes Java specifications.
• What is the EC?
• Guides the evolution of Java technology.
• Approves and reviews specifications.
• Composed of major stakeholders and diverse Java Community
members.
• Other EC Members:
• Oracle, IBM, Microsoft, AWS, SouJava, and more.

Speaking at Japanse JUGs
4

Speaking at Japanese JUGs
• English sessions are possible
• Since 2017 and the start of JOnsen, more English sessions in
Japanese conferences
• Events are not limited to Tokyo and Osaka
• They can also be held in other cities

Unique Features of Events in Japan
• Highly organized event management
• Community-driven events with hundreds of participants
• Attendees are polite and deeply focused on learning
• Few questions during Q&A but:
• Attendees actively take notes
• Many conduct further research independently after sessions

JJUG CCC
• Community conference organized by JJUG
• Started in 2007
• English sessions
• 600 attendees
• 57 sessions, 8 tracks
• One-day conference
• Twice a year (Spring, Fall)
• Held in Tokyo
• Free
• Last event website: https://ccc2024fall.java-users.jp/

Speaking at JJUG CCC
• Next event on June 7th (CfP closed)
• Submit proposals for Fall if interested
• Call for Proposals (CfP):
• Spring: February
• Fall: August

Next JOnsen Event
• Dates: June 13th-15th
• Venue: Japanese style ryokan in Aomori (Northern Japan)
• Website: https://www.jonsen.jp/

Next JJUG CCC and JOnsen
• JJUG CCC: June 7th
• JOnsen: June 13th-15th
• Explore Japan in between the events

When Visiting Japan
• If you are traveling to Japan and want to speak at a JUG
• Contact me (via X, Facebook, or LinkedIn)
•
• I can connect you with the right people based on where you
are staying.
• This has happened before, even last year
jyukutyo

Current Status of Japanese Software Engineers
• Difficulty in speaking and understanding English due to the
education system
• More pronounced compared to neighboring East Asian countries
• Fewer Japanese attendees at English sessions
• Cultural background leads to fewer questions during Q&A
• English skills improving, especially among the younger
generation

Wrap Up
5

Stepping Beyond the Comfort Zone
• Started as a developer, founded a JUG, and became its leader.
• Speaking as part of JUG activities led to becoming a Java
Champion.
• Constantly stepped out of my comfort zone, expanding it bit by
bit.
• Today, I'm presenting in English, my second language.
• With every experience, the second time becomes much easier.

The Community Helps You Take That First Step
• It's hard to take that first step alone.
• Joining a community makes it easier.
• See others in similar situations taking on challenges.
• Get to know people and feel at ease with the environment.
• Lower the barrier to becoming a speaker.
• Even small steps with the community can add up to significant
progress.

Java in Japan: A Journey of Community, Culture, and Global Integration (JavaOne 2025)

Java in Japan: A Journey of Community, Culture, and Global Integration (JavaOne 2025)

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