Langchain4j & Ollama - Integrating LLMs with Java programs {Workshop} @ OpenSlava 2025

Slides from my workshop at OpenSlava 2025 (October 15th) titled "Langchain4j & Ollama - Integrating LLMs with Java programs".
The code, including the step-by-step guidance is available here: https://github.com/deors/workshop-langchain4j

Transcript

1. Langchain4j & Ollama: Integrating LLMs with Java programs [Workshop] OpenSlava 15/10/2025
3. Associate Director – Software Engineering – Accenture Iberia Lead – DevOps & Platform Engineering Enterprise & Systems Architecture – Advanced Technology Center Java Global Community of Practice Java Champion Very active with open source and technology communities: Co-organizer – MálagaJUG / BoquerónSec Co-organizer – OpenSouthCode / OpenSouthKids Codemotion Ambassador @deors.bsky.social in/deors Jorge Hidalgo Copyright © 2025 Jorge Hidalgo – CC BY 4.0 3
4. Langchain4j & Ollama in a nutshell
5. Langchain4j Library to simplify integration of AI- based systems into Java programs https://github.com/langchain4j/langchain4j https://docs.langchain4j.dev/
6. Langchain4j “Hello World” public class OpenAiHelloWorld { void main() { // OpenAI model ChatLanguageModel model = OpenAiChatModel .withApiKey(”YOUR_OPENAI_API_KEY")); // the first prompt var message = "Hello world!"; System.out.println("\n>>> " + message); var answer = model.generate(message); System.out.println(answer); } }
7. Ollama Platform to manage and run language models locally (among other things) https://github.com/ollama/ollama https://ollama.com/
8. Ollama Inspect the model registry Download a model Upgrade it regularly Manage multiple versions of a given model Create your own models Fine-tune an existing model Run a model locally (CPU and GPU) Serve models exposing a REST API Things that can be done with Ollama
9. Show me the code!
10. 10 https://github.com/deors/workshop-langchain4j
11. Any final question? (and maybe some answers)
12. THANK YOU!