https://foojay.io/Foojay is a place for Friends Of OpenJDK, providing free, reference materials and blogs for daily Java usage.Hugoen-usSun, 20 Sep 2026 05:51:17 +0000https://foojay.io/today/world-geography-gotchas/Sun, 20 Sep 2026 05:51:17 +0000Nicolas FrankelTutorialshttps://foojay.io/today/world-geography-gotchas/Years ago, a colleague of mine told me about two pockets of foreign land surrounded by Switzerland: Campione d'Italia and Büsingen am Hochrhein,…https://foojay.io/today/boxlang-1-17-0-released-module-inception-cli-checker-jar-loading-and-much-more/Thu, 17 Sep 2026 20:20:32 +0000Cristobal EscobarAIBoxLangDeveloper ToolsGenAIJavaTestingToolshttps://foojay.io/today/boxlang-1-17-0-released-module-inception-cli-checker-jar-loading-and-much-more/BoxLang has always been an extensible language. As of 1.17.0, it is a hierarchically extensible one. Modules can now contain other modules; aka Module…https://foojay.io/today/whats-new-in-the-september-2026-azul-payara-release/Wed, 16 Sep 2026 16:46:54 +0000Dominika TasarzJakarta EEPayarahttps://foojay.io/today/whats-new-in-the-september-2026-azul-payara-release/MicroProfile 7.1 lands on the commercial lines, OpenTracing is removed, and Jakarta Agentic AI reaches Payara Micro in the September Azul Payara release.https://foojay.io/today/can-you-explain-the-diff-your-ai-agent-just-wrote/Tue, 15 Sep 2026 14:12:01 +0000Viktoria EvdokimovaAIIntelliJ IDEAJavaKotlinLLMhttps://foojay.io/today/can-you-explain-the-diff-your-ai-agent-just-wrote/Every Java developer has been in a code review where the question is simple: What does this method do? The answer used to tell you something.https://foojay.io/today/how-i-built-an-ai-assistant-for-my-career-with-java-spring-ai-and-mongodb/Tue, 15 Sep 2026 11:51:17 +0000Ricardo MelloAIDatabasesJavaMongohttps://foojay.io/today/how-i-built-an-ai-assistant-for-my-career-with-java-spring-ai-and-mongodb/How one developer built a personal AI assistant in Java using Spring AI, MongoDB Vector Search, conversation memory, and tool calling with Calendly.https://foojay.io/today/hello-java-27-have-you-been-working-out/Tue, 15 Sep 2026 08:00:00 +0000Hanno EmbregtsJavaJava CoreJEPshttps://foojay.io/today/hello-java-27-have-you-been-working-out/Java 27 is like that friend that you haven't seen all summer, and when you finally see them again it's clear that they spent a lot of time in the gym. Bringing numerous improvements to performance and security, this version of Java seems to be in top shape. This post has all the info!https://foojay.io/today/foojay-podcast-101/Mon, 14 Sep 2026 06:11:42 +0000Frank DelporteSimon RitterJavaJava CoreOpenJDKPodcasthttps://foojay.io/today/foojay-podcast-101/JDK 27 arrives on 15 September 2026, and it is a feature release rather than a Long-Term Support one. That distinction matters less than it sounds: as…https://foojay.io/today/come-for-java-get-a-whole-lot-more/Fri, 11 Sep 2026 09:33:46 +0000Richard FichtnerConferenceEventsJavaJUGshttps://foojay.io/today/come-for-java-get-a-whole-lot-more/JCON USA returns inside IBM TechXchange 2026 with two rooms of deep Java content, a dedicated community home, and direct access to one of the years…https://foojay.io/today/reflection-free-serialization-on-the-jvm-four-formats-in-avro-out/Thu, 10 Sep 2026 06:56:00 +0000Dmitry MoskalyukData EngineeringJavaKotlinhttps://foojay.io/today/reflection-free-serialization-on-the-jvm-four-formats-in-avro-out/I run a model layer that accepts the same business data in JSON, XML, YAML, and TOML and converts it all to Avro. The project was greenfield, so the…https://foojay.io/today/one-base-url-many-coding-agents-what-an-openai-compatible-gateway-looks-like-from-java-net-http/Wed, 09 Sep 2026 16:09:53 +0000Viktoria EvdokimovaAIDebuggingIntelliJ IDEAJavaJava BeginnerJava CoreJavaFXJavaProKotlinLLMMachine LearningRelease Noteshttps://foojay.io/today/one-base-url-many-coding-agents-what-an-openai-compatible-gateway-looks-like-from-java-net-http/Somewhere in every coding agent there is an HTTP client. Claude Code, Codex, Cursor, Cline, OpenCode: strip away the terminal UI or the editor pane and…https://foojay.io/today/masking-a-jvm-thread-dump-without-breaking-the-analysis/Wed, 09 Sep 2026 07:32:00 +0000Felipe MaschioJavaJava CoreSecurityhttps://foojay.io/today/masking-a-jvm-thread-dump-without-breaking-the-analysis/A few weeks ago I posted on r/java about detecting virtual thread pinning from a plain thread dump. The technical discussion was fine. The comment that…https://foojay.io/today/debugging-is-invariant-discovery-what-one-kafka-session-taught-us-about-ai-agents/Tue, 08 Sep 2026 14:14:36 +0000Viktoria EvdokimovaAIDebuggingGenAIJakarta EEJavaJava BeginnerJava CoreJavaFXJavaProLLMhttps://foojay.io/today/debugging-is-invariant-discovery-what-one-kafka-session-taught-us-about-ai-agents/Every Java team has a sentence like this one somewhere: Any operation on a TID must go through the single asynchronous path and must not let TMS and EMV…https://foojay.io/today/community-spotlight-boxlang-express-brings-node-style-http-to-the-jvm/Tue, 08 Sep 2026 11:25:18 +0000Cristobal EscobarBoxLangDeveloper ToolsJavaJava CoreMicroservicesToolshttps://foojay.io/today/community-spotlight-boxlang-express-brings-node-style-http-to-the-jvm/If you've spent years in Spring Boot, Micronaut, or Jakarta EE, "web framework" usually means a servlet container, an embedded Tomcat or Netty, a build…https://foojay.io/today/commit-created-no-no-no-what-the-the-agents-word-needs-external-verification-what-the-mistake-costs/Tue, 08 Sep 2026 08:54:03 +0000Viktoria EvdokimovaAgileAIJavaJava BeginnerJava CoreJavaFXJavaProKotlinLLMMachine Learninghttps://foojay.io/today/commit-created-no-no-no-what-the-the-agents-word-needs-external-verification-what-the-mistake-costs/A detailed report reads like proof. The agent lists the files it touched, names the branch, quotes a commit hash, adds a test count and closes with…https://foojay.io/today/from-opentelemetry-to-duckdb/Tue, 08 Sep 2026 08:29:37 +0000Geertjan WielengaDeveloper ToolsDuckDBOpenTelemetryPerformancehttps://foojay.io/today/from-opentelemetry-to-duckdb/Observability platforms generally expect you to do your analysis inside them, using their query language and their dashboards. That works for the…https://foojay.io/today/featured-foojay-authors-for-september-2026/Mon, 07 Sep 2026 08:38:56 +0000Frank DelporteFoojayhttps://foojay.io/today/featured-foojay-authors-for-september-2026/Our Featured Authors for September are Marit van Dijk and Graeme Robinson. Here is what they write about, and where to start reading.https://foojay.io/today/bringing-raspberry-pico-to-quarkus-with-firmata/Mon, 07 Sep 2026 06:06:42 +0000Igor De SouzaEmbeddedQuarkushttps://foojay.io/today/bringing-raspberry-pico-to-quarkus-with-firmata/Java applications are usually associated with APIs, databases, messaging systems, and cloud infrastructure. But Java can also interact with the physical…https://foojay.io/today/build-an-ai-agent-from-scratch/Mon, 07 Sep 2026 05:52:13 +0000Nicolas FrankelAIBook Reviewhttps://foojay.io/today/build-an-ai-agent-from-scratch/This review is about Build an AI Agent (From Scratch) by Jungjun Hur and Younghee Song from Manning. Facts 10 chapters $29.29 (at the time of this…https://foojay.io/today/from-spec-driven-development-to-living-specifications-in-java-projects/Fri, 04 Sep 2026 05:51:45 +0000Maximillian ArrudaAIDeveloper ToolsGenAIJavahttps://foojay.io/today/from-spec-driven-development-to-living-specifications-in-java-projects/From Spec-Driven Development to Living Specifications in Java Projects Coding agents have changed the speed at which we can produce software. But…https://foojay.io/today/building-an-agentic-warehouse-management-system-part-3-tools-decisions-and-actions/Thu, 03 Sep 2026 16:50:36 +0000Ricardo MelloAIhttps://foojay.io/today/building-an-agentic-warehouse-management-system-part-3-tools-decisions-and-actions/In this third and final part, we will build on the execution plan created in Part 2 and focus on the remaining stages of the agent workflow. We will see how each task is executed using controlled tools, how operational and business context is gathered, how the replenishment decision is made, and how the agent acts on that decision when necessary.https://foojay.io/today/building-an-agentic-warehouse-management-system-part-2-java-and-spring-ai/Thu, 03 Sep 2026 16:39:59 +0000Ricardo MelloAIhttps://foojay.io/today/building-an-agentic-warehouse-management-system-part-2-java-and-spring-ai/We will look at how the agent is built with Java and Spring AI, how its capabilities and boundaries are defined, how it is triggered by the WMS, and how the planner turns the agent’s goal into an execution plan.https://foojay.io/today/building-an-agentic-warehouse-management-system-part-1-where-ai-agents-add-value/Thu, 03 Sep 2026 16:23:14 +0000Ricardo MelloAIJavaMongohttps://foojay.io/today/building-an-agentic-warehouse-management-system-part-1-where-ai-agents-add-value/With this project, I am not trying to build a complete WMS. Instead, I want to use a logistics scenario I know well to explore how an AI agent can become part of a real business workflow and where it can add value. In this first part, we will introduce the WMS scenario and identify where an AI agent can help. In Part 2, we will define and connect the agent using Java and Spring AI. Finally, in Part 3, we will execute the plan, gather context, make the replenishment decision, and act when necessary.https://foojay.io/today/did-your-ai-agent-run-the-debugger-one-jvm-bug-two-agent-runs/Thu, 03 Sep 2026 13:48:32 +0000Viktoria EvdokimovaAIGenAIJavaJava CoreJavaFXJavaProKotlinLLMhttps://foojay.io/today/did-your-ai-agent-run-the-debugger-one-jvm-bug-two-agent-runs/Java developers reach for the debugger without thinking about it. Set a breakpoint, run the failing test, look at the variables, then decide what to…https://foojay.io/today/no-database-operations-found-what-writing-a-spring-boot-analyzer-taught-me-about-spring/Thu, 03 Sep 2026 06:26:00 +0000Braham ShaktiDebuggingDeveloper ToolsJavaSpringhttps://foojay.io/today/no-database-operations-found-what-writing-a-spring-boot-analyzer-taught-me-about-spring/I spent months building a static analyzer that answers one question about a Spring Boot codebase: if I change this endpoint, what does the change reach?https://foojay.io/today/mongodb-search-server-improved/Wed, 02 Sep 2026 10:00:00 +0000Erik HatcherMongohttps://foojay.io/today/mongodb-search-server-improved/The MongoDB Search Server for Java adds faceting, sorting, highlighting, weighted fields, and negative filters, with BSON pipeline tips and Docker deployment.https://foojay.io/today/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5/Tue, 01 Sep 2026 14:07:36 +0000Graeme RobinsonDatabasesMongohttps://foojay.io/today/aggregation-optimization-in-mongodb-sorting-with-indexes-part-5/Part 5 of our aggregation optimization series: swapping an explicit $sort for an index-backed sort cut MongoDB query time from 51ms to 14mshttps://foojay.io/today/announcing-bx-word-native-microsoft-word-automation-for-boxlang/Tue, 01 Sep 2026 11:31:16 +0000Cristobal EscobarBoxLangDeveloper ToolsJavaLibraryToolshttps://foojay.io/today/announcing-bx-word-native-microsoft-word-automation-for-boxlang/Every enterprise runs on Word documents. Contracts. RFPs. Proposals. Board reports. Offer letters. HR handbooks. Compliance policies. Invoices. Statements…https://foojay.io/today/aggregation-optimization-in-mongodb-data-duplication-to-improve-read-performance-part-4/Mon, 31 Aug 2026 14:45:04 +0000Graeme RobinsonMongohttps://foojay.io/today/aggregation-optimization-in-mongodb-data-duplication-to-improve-read-performance-part-4/And why MongoDB might be a better relational database than you ever realized. Design reviews are one-on-one meetings where MongoDB experts deliver advice…https://foojay.io/today/javafx-links-of-august-2026/Mon, 31 Aug 2026 12:58:02 +0000Frank DelporteJavaFXhttps://foojay.io/today/javafx-links-of-august-2026/Here are the JavaFX LinksOfTheMonth of August 2026. We took a summer break, so there was only one "Links Of The Week" this month, and it covers…https://foojay.io/today/ai-assisted-genealogy/Mon, 31 Aug 2026 05:51:48 +0000Nicolas FrankelAIhttps://foojay.io/today/ai-assisted-genealogy/My son recently came to me to brag about using AI to find our ancestors. While the results were correct, I didn't learn anything new, as it stopped at my…