Google Agent Development Kit (ADK) for Java with Gemma on Ollama

June 7, 2025

Google Agent Development Kit (ADK) for Java with Gemma on Ollama

Good news for Java developers! Google’s 🧰 Agent Development Kit (ADK), already popular in the 🐍 Python community, has officially arrived for ☕ Java.

This opens up exciting possibilities for millions of Java developers and enterprises looking to integrate powerful AI agent capabilities into their existing applications.

The initial version of the Java ADK directly supports the Gemini and Claude large language model (LLM) APIs already. In the Java ecosystem, LangChain4j is a popular framework (together with Spring AI) which already has many (20+ and more through the OpenAI API) integrations with other LLMs.

Guillaume Laforge started a LangChain4j Adapter for the Java ADK.

I decided to take that integration for a spin, and see if I can get this to work e.g. with the Gemma model, running it locally on Ollama. This is cool because it opens the door to many other possible models available on Ollama. And decentralized AI with optionality off the ⛅ cloud is important e.g. for more privacy sensitive use cases. (Personally I happen to think that 🔮 Gemini is currently the most awesome model - but choice is good!)

To ensure this solution is readily available for other users, I’ve incorporated some currently unmerged changes into a branch on a temporary fork (at https://github.com/enola-dev/adk-java). This setup allows us to distribute the necessary pieces via https://jitpack.io, while we work towards merging them into the official https://github.com/google/adk-java repository.

Curious to see it in action? Here’s how you can try out a simple command-line demo using the Java ADK with Gemma running locally on Ollama:

$ ollama pull gemma3:4b
$ git clone https://github.com/enola-dev/LearningADK
$ cd LangChain4j
$ ./run-cli.sh "hi, who are you and what can you do?"
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------------< dev.enola.adk:langchain4j >----------------------
[INFO] Building langchain4j 0.0.1-SNAPSHOT
[INFO]   from pom.xml
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- resources:3.3.1:resources (default-resources) @ langchain4j ---
[INFO] skip non existing resourceDirectory /home/vorburger/git/github.com/enola-dev/LearningADK/LangChain4j/src/main/resources
[INFO]
[INFO] --- compiler:3.13.0:compile (default-compile) @ langchain4j ---
[INFO] Nothing to compile - all classes are up to date.
[INFO]
[INFO] --- exec:3.5.1:java (default-cli) @ langchain4j ---
19:23:02.450 [dev.enola.adk.learn.OllamaWithoutTools.main()] INFO dev.langchain4j.http.client.log.LoggingHttpClient -- HTTP request:
- method: POST
- url: http://localhost:11434/api/chat
- headers: [Content-Type: application/json]
- body: {
  "model" : "gemma3:4b",
  "messages" : [ {
    "role" : "system",
    "content" : "You are an agent. Your internal name is multi_tool_agent. The description about you is Ollama"
  }, {
    "role" : "user",
    "content" : "hi, who are you and what can you do?"
  } ],
  "options" : {
    "stop" : [ ]
  },
  "stream" : false,
  "tools" : [ ]
}

19:23:19.445 [dev.enola.adk.learn.OllamaWithoutTools.main()] INFO dev.langchain4j.http.client.log.LoggingHttpClient -- HTTP response:
- status code: 200
- headers: [content-length: 1150], [content-type: application/json; charset=utf-8], [date: Sat, 07 Jun 2025 17:23:19 GMT]
- body: {"model":"gemma3:4b","created_at":"2025-06-07T17:23:19.433520588Z","message":{"role":"assistant","content":"Hello there! I'm Ollama, and I'm a multi-tool agent. Think of me as a helpful assistant that can do a wide variety of things. \n\nEssentially, I'm built to be flexible and adaptable. I can:\n\n*   **Answer your questions:** I can provide information on a huge range of topics, drawing on my knowledge base.\n*   **Generate text:** Need a poem, a story, a code snippet, or a different creative text format? I can generate it for you.\n*   **Translate languages:** I can translate text between many different languages.\n*   **Summarize text:**  I can condense large amounts of text into shorter, more manageable summaries.\n*   **And much more!** I'm still under development and constantly learning new things.\n\nBasically, I’m here to help you with whatever you need – just let me know what you have in mind!\n\nDo you want to try something out?"},"done_reason":"stop","done":true,"total_duration":16944139462,"load_duration":50999699,"prompt_eval_count":47,"prompt_eval_duration":1055489650,"eval_count":204,"eval_duration":15836903855}

Hello there! I'm Ollama, and I'm a multi-tool agent. Think of me as a helpful assistant that can do a wide variety of things.

Essentially, I'm built to be flexible and adaptable. I can:

*   **Answer your questions:** I can provide information on a huge range of topics, drawing on my knowledge base.
*   **Generate text:** Need a poem, a story, a code snippet, or a different creative text format? I can generate it for you.
*   **Translate languages:** I can translate text between many different languages.
*   **Summarize text:**  I can condense large amounts of text into shorter, more manageable summaries.
*   **And much more!** I'm still under development and constantly learning new things.

Basically, I’m here to help you with whatever you need – just let me know what you have in mind!

Do you want to try something out?
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  19.361 s
[INFO] Finished at: 2025-06-07T19:23:19+02:00
[INFO] ------------------------------------------------------------------------

$

There is still some work left to “fully integrate this upstream”, and perhaps iron out some early teething issues.

Enjoy!