Moises Gamio

One book instead of ten browser tabs: problem, clarifying questions, brute force, optimal solution, tests and follow-ups, all in one place. #CodingInterview #Java

Your API is documented with OpenAPI, and anyone who finds the URL can call it. Secure it with OAuth2, JWT and scopes in Spring Boot 4, with a working Swagger UI Authorize button. #SpringBoot #OAuth2

Last month's logs sit on the same fast, expensive disks as today's. That's money wasted. Build a hot-warm-cold Elasticsearch cluster that moves old logs to cheaper nodes automatically. #Elasticsearch #DevOps

Switch to an AI Career in Germany: MSIT's Funded Programs and a €500 Welcome Bonus codersite.dev/msit-ai-care... #msit #AgenticAI

Old images stopped being deleted, and nobody got an error. Why a Java app behind a load balancer gets Access Denied on a shared file server, and 3 ways to fix it. #Java #DevOps

Good code is not just written. It is designed. Learn how, with before-and-after Java you can run. #CleanCode #SoftwareDesign

A good programmer is someone who always looks both ways before crossing a one-way street. — Doug Linder #Programming #DevHumor

Attention to detail catches the bug before it becomes an incident. #Programming #Developer

Real questions. Real interviews. Real Java code with JUnit tests. Stop guessing what they'll ask. #CodingInterview #Java

Worst case is the guarantee your users care about. Learn Big O, Big Omega and Big Theta, and watch in a timing experiment how fast O(n²) falls behind. #Algorithms #Java

Get OOP wrong and you pay for years: tangled classes, features that break other features. The 4 pillars plus composition, with short Java examples. #OOP #Java

Your Java app works in testing, then falls over in production: requests pile up, connections run out. The fix is rarely "add servers". A playbook from cheapest fix to most expensive. #Java #Performance

The better your team understands design, the less time it spends fixing the same bug in two places. Try the 24-question design review. #SoftwareDesign #CodeReview

Most API problems aren't coding problems. They're design problems found too late. Design a real Finance API with OpenAPI 3 before anyone writes code, step by step. #OpenAPI #API

Coding interview problems solved step by step, Spring Boot API tutorials and software design case studies from real projects. All in Java, all with tests. #Java #CodingInterview

Your followers notice when the same post shows up twice in one afternoon. Random without repeats in Java: why random-and-retry breaks, and how a shuffle bag fixes it in O(1). #Java #SpringBoot

A list where you needed a map turns a millisecond lookup into a full scan. Which Java data structure to use and why, with a Big-O cheat sheet. #Java #DataStructures

Your Spring Boot API works. Can a stranger use it without asking you? Generate live Swagger UI docs from annotations, with every error response documented. #SpringBoot #API

Developers outside your team can't read your code. They read your API docs, and if those are wrong, they pick another provider. Document a Spring Boot API with OpenAPI 3. #SpringBoot #OpenAPI

Many non-OO legacy systems still do their job well. So do many monoliths that never became microservices. Working software is the goal, not the architecture trend. #SoftwareArchitecture #Microservices

Given 4751, return 1000. A warm-up interview question, yet many candidates miss int overflow and Integer.MIN_VALUE. From a slow countdown to an O(digits) solution in Java. #CodingInterview #Java

1 billion products. Find one by its GTIN. A linear scan needs up to a billion comparisons; a balanced binary search tree needs about 30. See how, in Java. #Java #Algorithms

If debugging is the process of removing software bugs, then programming must be the process of putting them in. — Edsger Dijkstra #Programming #Debugging

Every time you edit tested, working code to add a feature, you risk breaking it. Learn how the Open-Closed Principle lets you add new behavior without touching what already works. #SOLID #SpringBoot

SSLHandshakeException: Received fatal alert: handshake_failure. The server hung up, but why? Find the cause with javax.net.debug and openssl, and fix it in Java. #Java #TLS

This online assessment problem passes the examples, then times out on the hidden tests. Count items in closed compartments: from O(n·q) brute force to O(n + q) prefix sums. #CodingInterview #Java

Why are some codebases still easy to change after 5 years, while others need a rewrite after one? SOLID, DRY, KISS, YAGNI and more, each with a short Java example. #SoftwareDesign #Java

Technologies change. Design principles don't. Learn the ones that will still matter in 10 years. #SoftwareDesign #Java

In the end, financial decisions are not about getting rich. They are about getting what you want: getting happy. — Carl Richards #PersonalFinance #Money

Your AI coding agent starts every session from zero. Give it your build commands, architecture rules and guardrails. Free generator for CLAUDE.md, AGENTS.md, Cursor and Copilot. codersite.dev/tools/claude... #ClaudeCode #AI

Write code your future self will thank you for. #JavaDeveloper #software #design

Save Hundreds of Hours of Trial and Error #programming #coding #aceinterview

Avoid premature abstraction if you are not sure about the next change. #principles #systemdesign

A Path to Better Programming #java #coding #interview

Traverse a Graph with a Depth-First Search Algorithm #dfs #algorithm #graph

DRY. KISS. YAGNI. The three habits that separate seniors from juniors. #SoftwareDesign #software #TechBooks

Clean code is code that is easy to read, understand and maintain. Clean code makes software development predictable and increases the quality of the resulting product. #java #coding #interview

It is useful to think of a Docker image as an object that contains an OS filesystem & an app. It is like a virtual machine template -VMT. A VMT is a stopped virtual machine. A Docker image is a stopped container. If you are a developer, you can think of an image as a class #docker

Clean code can be read and enhanced by a developer other than its original author. #java #coding #interview

Production-ready Features — Spring Actuator #spring #programming

Don't comment bad code, rewrite it #cleancode #coding #programming

SOLID principles tell you how to arrange your functions into classes and how those classes should be interrelated #solid #objectoriented #programming

An Introduction to Functional Programming in Java #programming #functional #lambda

Big O Notation matters when we build an application for one user or millions of users. #java #coding #interview

How to establish an effective ubiquitous language in domain-driven design #ddd #language #design

Merge two Sorted Lists #java #coding #interview

Problem-Solving Efficiency. Hashmap provides efficient solutions for searching #programming

Optimize a basket in online purchases #java #coding #interview

Write unit tests first (TDD): Define behavior via tests before implementation for robust coverage. #programming

Learn the Reasons to use Graphs implementing the Depth-First Search algorithm. #dfs #algorithm #graph