langchain4j-demo/README.md

langchain4j-demo

Companion code for the ankurm.com LangChain4j posts. Every number and transcript quoted in a post comes from a file in a module's output/ folder, and the tests that write those files also assert the same facts, so the build fails when a claim stops being true.

Module	Post	What it shows
ai-services	LangChain4j AI Services with Spring Boot 4: Declarative LLM Interfaces	prompt templates, chat memory, tools, RAG, and the @MemoryId trap
spring-boot-ai-service	same post	@AiService on Spring Boot 4.1.1 with the 1.22.0-beta32 starter
agentic	Agentic Workflows with LangChain4j: Sequential, Parallel, Loop and Supervisor Agents	the five workflow builders, state passing by key, supervisor JSON, error recovery

Versions (verified on Maven Central, 2026-10-11)

Component	Version	Note
LangChain4j (langchain4j, langchain4j-core, BOM)	1.22.0	GA
LangChain4j beta modules (starters, embeddings, agentic)	1.22.0-beta32	beta only, no GA exists; the starter is built against Spring Boot 3.5.13
Spring Boot (spring-boot-ai-service)	4.1.1	GA
JDK	25 LTS
JUnit	6.1.3

Run

export JAVA_HOME=/path/to/jdk-25
mvn test                                       # everything
mvn test -pl agentic -am                        # one module (-am builds the parent and ai-services too)

No API key is needed. The tests use ScriptedChatModel, a deterministic stand-in for an LLM, so they can assert exactly which messages LangChain4j sent. Replace it with OpenAiChatModel or any other ChatModel and the AI Service interfaces do not change.

Each module writes its transcripts to <module>/output/ when you run the tests.