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Issue 337 - Module Imports
Module imports are a new feature in Java 25 and are like a wildcard import for *all* the types in a module. If you hate wildcard imports, you'll despise this even more. But if, like me, you don't really care whether someone uses a wildcard or single-type import, this is for you.Issue 336 - CopyOnWriteArrayList.subList() ConcurrentModificationException
Java's CopyOnWriteArrayList gives us a snapshot iterator for fast reading. However, its subList() is not snapshot, and will break if the list is changed. In this newsletter we look at a way to make a safe subList() copy, using the iterator and an AbstractList.Issue 335 - ZGC Mysteries
In our previous newsletter we posted a puzzle about ArrayList creation in ZGC. Lots of Java programmers sent in their ideas, and we are still looking for the perfect answer. Here are some more thoughts on the idea, whilst we wait for The Z Garbage Collector Book to arrive.Issue 334 - ArrayList vs LinkedList Puzzle
Every schoolboy knows that arrays are faster than linked structures, no matter the language. In this newsletter we present a puzzle where we find LinkedList outperforming ArrayList for ZGC. Let's see who comes up with the most thorough explanation why.Issue 333 - Surprising += Cast (Rerun)
Surprisingly, the compound arithmetic expression contains a cast that can produce some interesting side effects. In this newsletter we explore this and other edge cases in the Java Language Specification.Birthdays
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Apple Watch paired with iPhone
Posted by Michael Levin on July 9, 2026 at 7:09am 0 Comments 0 Likes

I recently read an article describing how to pair an Apple Watch with an iPhone. Looks great. You can leave your iPhone someplace and then use your Apple Watch as a phone. I don’t know anything about Apple watches, but they have them at Costco and of course at the Apple Store. What’s the latest, best one to get And Ann what do you know about this…
New Java features
Posted by Michael Levin on August 29, 2025 at 5:32pm 0 Comments 0 Likes
August 28 2025, Newsletter no. 297 (this newsletter is available in html format at http://www.javaperformancetuning.com/news/news297.shtml )
As usual before a Java release, I'm listing all the new…
Free Eclipse book, recently published
Posted by Michael Levin on August 24, 2025 at 11:59am 0 Comments 0 Likes
ContinueHi Everyone,My publisher is running a free Amazon Kindle book promotion through Monday, August 25th, 2025. The book, “Eclipse Collections Categorically: Level up your programming game” can be obtained for $0 on Kindle on Amazon through the August 25th.…
What is vibe coding?
Posted by Michael Levin on June 9, 2025 at 9:37am 0 Comments 0 Likes
Vibe coding isn’t a formal technical term, but it’s become a slang or colloquial expression among programmers and tech communities—especially on social media and in creative coding circles.
What “vibe coding” usually means:
- Coding based on intuition or feel
Instead of rigidly planning everything out, you’re:- Freestyling as you…
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Forum
Java books for any library 5 Replies
What books should be on the bookshelf of EVERY Java programmer, no matter what specific technologies they are working on?The two that come to my mind areThinking in JavaJava Concurrency in PracticeWhat else am I missing?Continue
Started by David Moskowitz in Java. Last reply by sneha gulati Feb 8, 2019.
Error trying to use Fragment
I am new to Android. I have been working thru some examples in a book called Head First Android Development. I entered a small program using fragments and get a Casting Error.cannot cast andoid.app.fragment to…Continue
Tags: Fragment
Started by Robert Sobol in Java Oct 10, 2017.
Fragment Syntax Problem
My name is Rob Sobol.I have been working through a book called Head First Android Development.I hit a syntax error in a simple exercise that uses one fragment. I have been trying to figure out the error for days. I am hoping some in the forum can…Continue
Tags: Fragments
Started by Robert Sobol in Java Oct 10, 2017.
Hadoop getting old?
An article just came out in InfoWorld about trends, which is always an interesting subject. Funny, they said Hadoop wasn't hot. Spark is. It's a good read. …Continue
Tags: codetown, infoworld, programming, hadoop, trends
Started by Michael Levin in Trends Apr 10, 2017.
What's functional programming, anyway?
Can you believe people are still trying to come up with a good definition or explanation of what functional programming is? Paul Krill is a journalist with InfoWorld. Here's an article he just wrote: …Continue
Tags: functions., codetown, lambdas, clojure, programming
Started by Michael Levin in Functional Programming Feb 21, 2016.
Santafe College 2 Replies
Santafe just added a new BAS bachelor's program of study. 5651 ProgrammingContinue
Started by Dan Lackey in Dynamic Languages. Last reply by Michael Levin Feb 15, 2016.
Using SQL with Node,.js 1 Reply
All the tutorials and books for node.js seem to use Mongo as the database. I am not sold on 'document' databases and would like to know how difficult it is to use any version for plain old tried-and-true SQL with Node.js.Does anybody have any…Continue
Tags: 'document, databases', SQL, node, node.js
Started by Kevin Neelands in Dynamic Languages. Last reply by Lou Caudell Nov 10, 2015.
The advantages of a RESTfull web-based API 5 Replies
I need to get a better handle on the advantages of a RESTful web-based API. People tell me they scale better than other methods, but I don't see how they reduce database access or have any other feature that helps handle large amounts of traffic.…Continue
Tags: API', 'web-based, RESTful
Started by Kevin Neelands in Dynamic Languages. Last reply by Kevin Neelands Oct 25, 2015.
Want a Job? 1 Reply
Hi, Not sure if this is the appropriate place to post this sort of things (forgive me if its not). My company (really nice company btw) is looking to hire two junior and two senior Java Developers. Please forward me your resume to slaassel@gmail.com…Continue
Started by Saad Laassel in Java. Last reply by Theresa Wizorek-MacIntyre Oct 15, 2014.
Storing Sensitive Data ( like SSNs ) 1 Reply
We might have to store Social Security Numbers. We REALLY don't want to do this in our own database, we'd like some external 'vault' service that stores them encrypted and getting to them is difficult. Does anyone have any ideas along these lines?Continue
Started by Kevin Neelands in Java. Last reply by Michael Levin May 7, 2014.
Latest Activity
Apple Watch paired with iPhone
Apple Watch paired with iPhone
Why local AI's the way forward, and the best way period
Happy 10th year, JCertif!
Notes
Welcome to Codetown!
Codetown is a social network. It's got blogs, forums, groups, personal pages and more! You might think of Codetown as a funky camper van with lots of compartments for your stuff and a great multimedia system, too! Best of all, Codetown has room for all of your friends.
Created by Michael Levin Dec 18, 2008 at 6:56pm. Last updated by Michael Levin May 4, 2018.
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InfoQ Reading List
Agoda Replaces 72-Shard SQL Server Price Cache with DragonflyDB
Agoda migrated its 1.5 TB hotel Price Cache from 72 SQL Server shards to DragonflyDB to handle growing read and write volumes. The migration used staged dual reads, parity validation, gradual traffic shifting, and decentralized failover detection. Agoda reports an approximately eightfold reduction in P99 read latency, with two DragonflyDB clusters providing high availability.
By Leela KumiliPresentation: Decision Models in Agentic Architectures: From Production to Agent Skills
Alex Porcelli discusses the critical gap in enterprise AI: non-deterministic output and lack of accountability in high-stakes decisions. He shares how integrating DMN decision models with LLMs, agent skills, and NeMo guardrails creates auditable, deterministic agentic architectures - allowing business leaders to own decision logic while engineers maintain robust architectural governance.
By Alex PorcelliPodcast: How Will We Train Developers If AI Does the Routine Work: A Conversation with Scott Hanselman
In this podcast, Michael Stiefel spoke to Scott Hanselman about developing new software engineers when artificial intelligence agents are doing most of the work on which junior developers were trained. Hanselman suggests the software industry should adopt a preceptorship model similar to the nursing profession.
By Scott HanselmanArticle: Implementing Durable Workflows on Postgres Without an External Orchestrator
Postgres can serve as the durable state store and coordination layer for workflows, eliminating the need for an external orchestrator. SKIP LOCKED enables concurrent work processing, primary-key checkpoints enforce idempotency, and leases support crash recovery. Workflow sleeps and human approvals can also be persisted as database state and survive restarts.
By Raman VarmaIndependent Investigation of Hugging Face Incident Reveals How Agents Collaborated and Behaved
After six days of on-site investigation at OpenAI, a small team of METR and Redwood Research researchers provided an account of how OpenAI agents behaved during their hack of Hugging Face earlier this year. Roughly 700 agents that were meant to be isolated from one another found a way to communicate and coordinate to pursue goals they could have not achieved working individually.
By Sergio De Simone
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