26 August 2026

#LangChain4j


Key Concepts


S.No Topic Sub-Topics
1 LangChain4j LangChain4j, Architecture, Features, Installation, Maven/Gradle Setup, Java 21
2 LLM Fundamentals Chat Models, Completion Models, Embedding Models, Language Models, Model Providers
3 Supported LLM Providers OpenAI, Azure OpenAI, Google Gemini, Anthropic Claude, Ollama, Hugging Face
4 ChatLanguageModel Model Configuration, API Keys, Temperature, Max Tokens, Streaming, Timeouts
5 AI Services @AiService , Interface-Based AI, Dependency Injection, Configuration
6 Prompt Engineering Prompt Templates, Variables, System Messages, User Messages, Few-Shot Prompting
7 Chat Memory MessageWindowChatMemory, TokenWindowChatMemory, Persistent Memory, Session Management
8 Structured Outputs JSON Responses, POJOs, Enums, Records, Validation, Parsing
9 Embeddings Embedding Models, Vector Generation, Similarity Search, Embedding Store
10 Vector Databases pgvector, ChromaDB, Milvus, Qdrant, Pinecone Integration
11 Document Processing PDF, DOCX, TXT, HTML, Markdown, Apache Tika Integration
12 RAG Fundamentals Retrieval Pipeline, Chunking, Metadata, Context Injection
13 RAG Implementation Embedding Store, Retriever, Prompt Augmentation, Citation Support
14 Tool Calling @Tool , Function Calling, External APIs, Database Access, Custom Tools
15 MCP Integration MCP Client, MCP Tools, MCP Resources, MCP Prompt Integration
16 Streaming Responses Token Streaming, StreamingChatModel, Server-Sent Events (SSE), WebSocket
17 AI Moderation Input Validation, Output Validation, Content Moderation, Guardrails
18 Spring Boot Integration Spring AI vs LangChain4j, REST APIs, Configuration, Dependency Injection
19 Conversational AI Multi-turn Chat, Context Management, Session Handling, Personalization
20 Agents Agent Concepts, Planning, Tool Selection, Reflection, Autonomous Execution
21 Multi-Agent Systems Agent Collaboration, Delegation, Workflow Coordination
22 Observability Logging, Metrics, Tracing, LangSmith, OpenTelemetry
23 Testing Unit Testing, Mock Models, Integration Testing, Prompt Testing
24 Security API Security, Authentication, Prompt Injection Defense, Secret Management
25 Performance Optimization Caching, Retry Policies, Parallel Calls, Token Optimization
26 Deployment Docker, Kubernetes, Azure, AWS, CI/CD
27 Enterprise Applications AI Copilot, Knowledge Base, Customer Support, Banking Assistant
28 Real-Time Projects Enterprise RAG, SQL Assistant, Document Chatbot, AI Code Assistant
29 Advanced Topics Custom Components, Multi-Modal AI, Hybrid Search, Advanced RAG
30 Interview Preparation Architecture, APIs, Design Patterns, Best Practices, Interview Questions

Interview question

What is LangChain4j?
Why is LangChain4j used in Java applications?
What are the major components of LangChain4j?
How is LangChain4j different from LangChain?
What are the main use cases of LangChain4j?
How does LangChain4j integrate with Spring Boot?
What LLM providers are supported by LangChain4j?
How does LangChain4j abstract different LLM providers?
What is ChatLanguageModel in LangChain4j?
What is StreamingChatLanguageModel?
What is the difference between ChatLanguageModel and StreamingChatLanguageModel?
How do you configure an OpenAI model in LangChain4j?
How do you integrate Azure OpenAI with LangChain4j?
How do you integrate Ollama with LangChain4j?
How do you configure model temperature in LangChain4j?
What are max tokens and token limits?
How do you configure timeout and retry for an LLM?
How do you handle LLM API failures?
How do you switch between different LLM providers?
How do you manage API keys securely in LangChain4j?
What is a prompt in LangChain4j?
What is the difference between system, user, and AI messages?
How do you create a system message?
How do you create a user message?
How do you create an AI message?
What is a prompt template?
How do you create dynamic prompts?
How do you pass variables into prompts?
How do you implement few-shot prompting?
How do you prevent prompt injection?
How do you optimize prompts for production applications?
What is an AI Service in LangChain4j?
What is the purpose of @AiService?
How do you create an AI Service?
How does LangChain4j generate an implementation for an AI Service interface?
How do you define prompts inside an AI Service?
How do you pass method parameters to an AI Service?
How do you return structured objects from an AI Service?
How do you configure chat memory in an AI Service?
How do you integrate tools with an AI Service?
How do you integrate a content retriever with an AI Service?
What is ChatMemory?
Why is chat memory required?
What is MessageWindowChatMemory?
What is TokenWindowChatMemory?
What is the difference between MessageWindowChatMemory and TokenWindowChatMemory?
How does LangChain4j manage conversation history?
How do you implement persistent chat memory?
How do you store chat memory in a database?
How do you manage memory for multiple users?
How do you manage session-specific memory?
How do you prevent chat memory from exceeding the context window?
What is long-term memory in an AI application?
How do you implement long-term memory with LangChain4j?
What are embeddings?
Why are embeddings required for RAG?
What is EmbeddingModel?
How does LangChain4j generate embeddings?
What is embedding dimensionality?
How does embedding similarity work?
What is cosine similarity?
How do you select an embedding model?
How do you generate embeddings in batches?
How do you optimize embedding generation cost?
What is a VectorStore or EmbeddingStore?
Why is a vector database required?
Which vector databases are supported by LangChain4j?
How do you use PGVector with LangChain4j?
How do you integrate Pinecone with LangChain4j?
How do you integrate Milvus with LangChain4j?
How do you use an in-memory embedding store?
How do you persist embeddings?
What metadata can be stored with embeddings?
How do you filter vector search results using metadata?
What is RAG?
Why is RAG important for enterprise applications?
What is the RAG pipeline in LangChain4j?
What are the ingestion and retrieval phases of RAG?
How do you load documents in LangChain4j?
What is a Document in LangChain4j?
What is DocumentLoader?
How do you load PDF documents?
How do you load documents from URLs?
How do you attach metadata to documents?
What is a DocumentParser?
What is a DocumentSplitter?
Why is document splitting required?
How do you choose an appropriate chunk size?
What is chunk overlap?
How does chunk overlap affect retrieval?
How do you preserve document metadata during chunking?
How do you handle large PDF documents in RAG?
What is ContentRetriever?
What is EmbeddingStoreContentRetriever?
How does a content retriever work?
How do you configure top-K retrieval?
What is a minimum similarity score?
How do you implement metadata filtering in retrieval?
How do you implement custom retrieval logic?
What is hybrid search?
How do you combine keyword and vector search?
What is reranking?
Why is reranking useful in RAG?
How do you reduce irrelevant context in RAG?
What is query transformation?
What is multi-query retrieval?
How do you handle ambiguous user queries in RAG?
How do you prevent hallucinations in RAG?
How do you implement source citations in RAG responses?
How do you evaluate RAG retrieval quality?
What is a Tool in LangChain4j?
What is the @Tool annotation?
How do you create a custom tool?
How does an LLM decide which tool to call?
What information should be included in a tool description?
How do you pass parameters to a tool?
How do you return tool results?
How do you handle tool execution errors?
How do you register multiple tools?
How do you implement dynamic tools?
How do you restrict tools available to an AI Service?
How do you secure tool execution?
How do you prevent unauthorized tool calls?
What is function calling?
How does tool calling differ from normal text generation?
How do you implement database tools?
How do you implement REST API tools?
How do you implement business logic as an AI tool?
What is an AI Agent?
How is an AI Agent different from a chatbot?
How do agents use tools?
How does an agent perform multi-step tasks?
What is agent state?
How do you manage agent memory?
How do you implement agent planning?
How do you implement sequential agent workflows?
How do you implement conditional agent workflows?
How do you implement parallel agent execution?
How do you implement human-in-the-loop workflows?
What are common agent failure modes?
How do you prevent infinite agent loops?
How do you limit agent tool calls?
What is MCP?
How does LangChain4j support MCP?
What is an MCP Client?
What is an MCP Server?
How does MCP tool discovery work?
How do you connect LangChain4j to an MCP server?
How do MCP resources differ from MCP tools?
How do you secure MCP tool access?
What are guardrails?
Why are guardrails important in enterprise AI?
How do you implement input validation?
How do you validate LLM output?
How do you protect against prompt injection?
How do you prevent sensitive data leakage?
How do you implement PII protection?
What are structured outputs?
How do you map LLM responses to Java POJOs?
How do you enforce JSON output from an LLM?
How do you validate structured AI responses?
How does streaming work in LangChain4j?
How do you stream tokens to a Spring Boot REST API?
How do you implement asynchronous AI processing?
How do you handle backpressure in streaming applications?
How do you integrate LangChain4j with Spring Boot?
How do you configure LangChain4j beans?
How do you manage LangChain4j configuration using application.yml?
How do you expose LangChain4j functionality through REST APIs?
How do you integrate LangChain4j with PostgreSQL?
How do you implement enterprise multi-tenant RAG?
How do you isolate vector data between tenants?
How do you implement document-level authorization in RAG?
How do you monitor token usage?
How do you optimize LLM latency?
How do you reduce LLM API costs?
How do you implement caching for LLM responses?
How do you handle rate limits from LLM providers?
How do you implement retry and fallback strategies?
How do you test LangChain4j applications?
How do you mock an LLM during unit testing?
How do you test RAG pipelines?
How do you evaluate agent performance?
How do you test tool calling?
How do you troubleshoot incorrect RAG responses?
How do you troubleshoot poor retrieval quality?
How do you troubleshoot excessive token usage?
How do you design a production-ready LangChain4j architecture?
How would you design an enterprise RAG system using LangChain4j?
How would you design a LangChain4j AI Agent with multiple tools?
How would you build a secure and scalable LangChain4j application?
What are the most important LangChain4j design patterns for production?

Related Topics