RAG From Scratch in Java

📰 Dev.to · Puneet Gupta

Learn to build a retrieval-augmented generation (RAG) model from scratch in Java, understanding key components like chunking, embeddings, and vector search.

advanced Published 5 Jul 2026
Action Steps
  1. Build a chunking algorithm to split input text into manageable pieces using Java.
  2. Create a custom embedding layer to convert text chunks into numerical vectors.
  3. Implement a hand-rolled cosine-similarity vector search to find relevant chunks.
  4. Develop a reranking system to refine the search results based on relevance and context.
  5. Compare the performance of the RAG model with a larger context window to understand its advantages.
Who Needs to Know This

This tutorial benefits NLP engineers and software developers who want to implement RAG models in Java for improved text generation tasks. It's ideal for teams working on chatbots, language translation, or text summarization projects.

Key Insight

💡 RAG models can outperform larger context windows in certain scenarios by leveraging retrieval-augmented generation techniques.

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🚀 Build RAG from scratch in Java! Learn chunking, embeddings, vector search, and reranking for improved text generation. #RAG #Java #NLP

Key Takeaways

Learn to build a retrieval-augmented generation (RAG) model from scratch in Java, understanding key components like chunking, embeddings, and vector search.

Full Article

Building retrieval-augmented generation from first principles in Java: chunking, embeddings, a hand-rolled cosine-similarity vector search, reranking, and when RAG beats a bigger context window.
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