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Ruvimbo Delia Hakata
Ruvimbo Delia Hakata

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Building GenAI Apps in Java

This article is a summation of the lessons from my demo/talk titled: Building Production-Ready GenAI Apps in Java with Vertex AI.When I was prepared to deliver this session online session earlier, I had one clear goal: to move past the hype. Too often, conversations about generative AI get stuck at “look what this model can do.” I wanted to take it further to show how we can actually deliver business-ready applications that solve real problems inside organizations.

Why Java?

For this demo, I went with Java. I know it might raise eyebrows since Python dominates most AI conversations. But here’s the thing: across enterprise environments, especially in Africa, Java is still the backbone.

It powers banks, mobile apps, and core business systems. Python is great for rapid experiments, but when it comes to scalability, integration, and long-term maintainability, Java quietly does the heavy lifting.

By choosing Java, I wanted to make a point: if AI is going to bring real business value, it needs to live where the business already lives.

The Business Problem I Framed

I anchored the demo in a gaming scenario. Picture this: a mobile game with thousands of active players. The company is swimming in data demographics, session times, devices, revenue per user. But raw data doesn’t drive growth.

The marketing team doesn’t want CSVs. They want to know how to reach their players.

So, I built a persona generator:

  • Data ingestion: demographics + behavior from GA4 API
  • Context enrichment: a RAG pipeline that blends analytics with internal data (support tickets, logs)
  • Persona creation: Vertex AI generating customer personas linked to business goals

The output? Not just charts but stories, pain points, and strategies. That’s the jump from numbers to business clarity.

The Toolchain

The stack was simple but effective:

  • GA4 API →customer behavior data
  • Java service layer → prompt orchestration
  • Vertex AI (Gemini models) → persona generation
  • Cloud Run → deployment with one command

A few things I had to emphasize in the session:

  • Data quality drives output quality. I had a value a big “97%” bold on a slide for this reason.
  • Prompts = business logic. Phrase them wrong, and you’ll get fluff. Phrase them right, and you’ll get insights.
  • AI without responsibility is reckless. Deploying without safety, governance, and monitoring is like shipping code without testing.

Practical Guidance

If you want to try something similar: start with a real business problem. My demo solved customer personas generation deadlocks, but the same setup could power sentiment tracking for PR, financial event assistants, or multilingual copy for marketing.

The Takeaway

Generative AI is not a lab experiment anymore. It’s becoming embedded in business processes—funding is flowing, adoption is increasing, and teams using it daily are experiencing productivity boosts.

Production-ready AI isn’t about the model. It’s about pipelines, integration, and responsibility. That’s what separates flashy demos from real business impact.

The companies that win with AI won’t just use it—they’ll integrate it.

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