LangChain4j AI Services Patterns

LangChain4j AI Services Patterns

This skill provides guidance for building declarative AI Services with LangChain4j using interface-based patterns, annotations for system and user messages, memory management, tools integration, and advanced AI application patterns that abstract away low-level LLM interactions.

Overview

LangChain4j AI Services define AI functionality using Java interfaces with annotations, providing type-safe, declarative AI with minimal boilerplate.

When to Use

Use this skill when:

• Building declarative AI services with minimal boilerplate using Java interfaces
• Creating type-safe conversational AI with memory management
• Implementing AI agents with function/tool calling capabilities
• Designing AI services returning structured data (enums, POJOs, lists)
• Integrating RAG patterns declaratively

Instructions

Follow these steps to create declarative AI Services with LangChain4j:

1. Define AI Service Interface

Create a Java interface with method signatures for AI interactions:

interface Assistant {
    String chat(String userMessage);
}

2. Add Annotations for System and User Messages

Use @SystemMessage and @UserMessage annotations to define prompts:

interface CustomerSupportBot {
    @SystemMessage("You are a helpful customer support agent for TechCorp")
    String handleInquiry(String customerMessage);