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JavaGuide

Backend tech guide and AI engineering practice covering fundamentals, databases, distributed systems, high concurrency, system design, plus AI agents and large-model engineering.

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Latest from JavaGuide

72 recent articles

JavaGuide

Apr 14, 2026 · Artificial Intelligence

Interview Question: How to Build Prompt Engineering for an Agent and Defend Against Malicious Prompt Injection

The article explains how industrial‑grade AI agents require structured prompt engineering, chain‑of‑thought reasoning, task decomposition, and a three‑layer defense (sandbox, prompt isolation, and human approval) to prevent prompt‑injection attacks, while also covering context engineering, retrieval‑augmented generation, and tool design best practices.

Agent designChain-of-ThoughtLLM security

0 likes · 23 min read

Interview Question: How to Build Prompt Engineering for an Agent and Defend Against Malicious Prompt Injection

JavaGuide

Apr 7, 2026 · Information Security

Why Brute‑Force Won’t Cut It for Sensitive‑Word Filtering (And What Actually Works)

The article walks through the evolution of sensitive‑word filtering—from naïve brute‑force scanning to Trie, Aho‑Corasick automaton, Double‑Array Trie, and DFA implementations—detailing their algorithms, time/space complexities, concrete Java code examples, performance trade‑offs, high‑concurrency optimizations, and practical production advice for building a robust content‑moderation system.

Aho-CorasickDFAJava

0 likes · 26 min read

Why Brute‑Force Won’t Cut It for Sensitive‑Word Filtering (And What Actually Works)

JavaGuide

Mar 30, 2026 · Backend Development

Interviewers Ask About Claude Code Skills—What If You Haven’t Used /simplify?

The article explains the built‑in Claude Code /simplify command, how it uses three parallel AI agents to review and automatically fix code, demonstrates real‑world bugs it uncovered in Java projects, compares it with traditional linters, and offers practical tips and integration guidance.

/simplifyAI agentsClaude Code

0 likes · 16 min read

Interviewers Ask About Claude Code Skills—What If You Haven’t Used /simplify?

JavaGuide

Mar 18, 2026 · Artificial Intelligence

Why Build Your Own Claude Code Agent? A Step‑by‑Step Walkthrough

This article explores the Learn Claude Code website, breaking down the universal agent loop into twelve incremental versions, demonstrating language‑agnostic implementations in Python and Java, and detailing progressive capabilities—from basic tool integration to memory compression, concurrency, and multi‑agent collaboration.

AI agentAgent LoopClaude

0 likes · 9 min read

Why Build Your Own Claude Code Agent? A Step‑by‑Step Walkthrough

JavaGuide

Mar 17, 2026 · Backend Development

Boost Java Backend Productivity with IDEA + Qoder: From Days to Minutes

This article demonstrates how the Qoder AI plugin for JetBrains IDEA can transform lengthy backend tasks—such as deep‑pagination optimization and legacy code refactoring—into rapid, automated workflows, cutting development time from days to under ten minutes while preserving code quality.

AI CodingIDEAJava Backend

0 likes · 18 min read

Boost Java Backend Productivity with IDEA + Qoder: From Days to Minutes

JavaGuide

Mar 9, 2026 · Databases

Does SELECT * Always Invalidate Indexes? Why Some Teams Ban It

While many believe that using SELECT * inevitably disables indexes, MySQL’s optimizer only skips indexes when a full table scan is cheaper, and patterns such as violating the left‑most prefix, applying functions or implicit casts, leading‑wildcard LIKE, OR/IN misuse, and mismatched ORDER BY can cause index invalidation, prompting some companies to forbid SELECT * in production.

DatabaseMySQLPerformance Tuning

0 likes · 14 min read

Does SELECT * Always Invalidate Indexes? Why Some Teams Ban It

JavaGuide

Feb 27, 2026 · Artificial Intelligence

Why I Dropped Opus 4.6 for MiniMax M2.5: Real‑World Cost and Performance Test

The author, a heavy user of AI agents for daily code refactoring, compares the expensive Opus 4.6 with the budget‑friendly MiniMax M2.5, showing how a mixed‑model strategy cuts costs dramatically while maintaining speed and quality across two full‑stack development case studies.

AI CodingAgent ArchitectureMiniMax M2.5

0 likes · 14 min read

Why I Dropped Opus 4.6 for MiniMax M2.5: Real‑World Cost and Performance Test

JavaGuide

Feb 11, 2026 · Backend Development

Do ThreadLocal Values Fail in Asynchronous Scenarios? An Interviewer's Trick Question Explained

This article explains why ThreadLocal values are not automatically transferred in asynchronous or thread‑pool contexts, compares JDK's InheritableThreadLocal with Alibaba's TransmittableThreadLocal (TTL), and shows how TTL captures, replays, and restores context safely with code examples and diagrams.

InheritableThreadLocalJava concurrencyThreadLocal

0 likes · 13 min read

Do ThreadLocal Values Fail in Asynchronous Scenarios? An Interviewer's Trick Question Explained

JavaGuide

Jan 15, 2026 · Interview Experience

Lost the Courage to Switch Jobs After Three Years in a State-Owned Enterprise?

The author explains why state-owned enterprises are not always stable, why their low‑tech projects hinder interview performance, and offers concrete steps—such as adding Redis caching, multithreading, and using the STAR method—to turn a modest Java background into compelling interview material.

BackendJavaRedis

0 likes · 6 min read

Lost the Courage to Switch Jobs After Three Years in a State-Owned Enterprise?

JavaGuide

Jan 13, 2026 · Backend Development

Claude Code Generates Unexpected Bugs: 4 Real-World Spring Pitfalls and Fixes

During a Spring‑based interview platform project, the author discovered four typical bugs introduced by Claude Code—transactional self‑invocation loss, AI‑generated NullPointerExceptions, async task failures after entity deletion, and Redis Stream message buildup—and explains the root causes and concrete remediation steps.

@Async@TransactionalAI code generation

0 likes · 11 min read

Claude Code Generates Unexpected Bugs: 4 Real-World Spring Pitfalls and Fixes