Author

Selected Java Interview Questions

A professional Java tech channel sharing common knowledge to help developers fill gaps. Follow us!

1.5k

Articles

Likes

3.5k

Views

Comments

Latest from Selected Java Interview Questions

100 recent articles max

Selected Java Interview Questions

Oct 24, 2025 · Backend Development

How to Secure a Spring Boot Application with Spring Security and JWT

This step‑by‑step guide shows how to integrate Spring Security into a Spring Boot project, configure Maven dependencies, define User, Role and Permission entities, set up MyBatis mappers, implement JWT generation and validation, and build the service, controller, and configuration layers for a complete authentication system.

AuthenticationAuthorizationJWT

0 likes · 28 min read

How to Secure a Spring Boot Application with Spring Security and JWT

Selected Java Interview Questions

Oct 22, 2025 · Backend Development

How to Seamlessly Migrate a Spring Boot 3.0 App from HTTP to HTTPS

This comprehensive guide walks you through migrating a Spring Boot 3.0 JavaWeb application from HTTP to HTTPS, covering certificate acquisition (including Let’s Encrypt), conversion to Java keystore, Spring Boot and reverse‑proxy configuration, application adjustments, automated renewal, testing, rollback, and ongoing monitoring.

CertbotHTTPSJava

0 likes · 13 min read

How to Seamlessly Migrate a Spring Boot 3.0 App from HTTP to HTTPS

Selected Java Interview Questions

Oct 21, 2025 · Big Data

How to Sync Massive MySQL Datasets Efficiently with DataX

This guide walks through the challenges of synchronizing tens of millions of records between heterogeneous MySQL databases, explains why traditional mysqldump or file‑based methods fail, and provides a step‑by‑step tutorial on installing, configuring, and using Alibaba's open‑source DataX tool for both full and incremental data synchronization.

Data SynchronizationDataXETL

0 likes · 15 min read

How to Sync Massive MySQL Datasets Efficiently with DataX

Selected Java Interview Questions

Oct 19, 2025 · Backend Development

How to Prevent Duplicate Order Submissions with Token + Redis Lock in Spring Boot

This article explains why duplicate order submissions occur in e‑commerce systems and presents a comprehensive solution using request tokens, interface idempotency, and Redis‑based distributed locks, complete with Spring Boot code examples and advanced optimization tips.

duplicate submissionidempotencyorder processing

0 likes · 7 min read

How to Prevent Duplicate Order Submissions with Token + Redis Lock in Spring Boot

Selected Java Interview Questions

Oct 15, 2025 · Backend Development

How to Turbocharge Java Spring Boot Startup: From Seconds to Milliseconds

This article explains why Java applications often start slowly, identifies the main culprits such as excessive class loading, bloated JARs, and reflection, and provides a comprehensive set of JVM, Spring Boot, code‑level, and deployment optimizations—including lazy loading, auto‑configuration pruning, GraalVM native images, and container probes—to dramatically reduce startup time and ace interview questions.

JVMJavaPerformance Tuning

0 likes · 13 min read

How to Turbocharge Java Spring Boot Startup: From Seconds to Milliseconds

Selected Java Interview Questions

Oct 12, 2025 · Backend Development

Simplify Java Async Tasks with LatchUtils: A Clean Alternative to CountDownLatch

This article introduces LatchUtils, a lightweight Java utility that streamlines asynchronous task registration and waiting, compares it with manual CountDownLatch and CompletableFuture approaches, and demonstrates how it reduces boilerplate while keeping business logic clear and maintainable.

AsyncConcurrencyCountDownLatch

0 likes · 15 min read

Simplify Java Async Tasks with LatchUtils: A Clean Alternative to CountDownLatch

Selected Java Interview Questions

Oct 11, 2025 · Backend Development

Mastering QR Code Generation in Java: From Simple Tokens to Custom Logos

Learn how to generate various QR codes in Java—including login tokens, promotional URLs, and temporary visitor codes—by analyzing use cases, selecting the ZXing library, and following step‑by‑step code examples with best‑practice tips and common pitfalls.

Code TutorialJavaQR code

0 likes · 9 min read

Mastering QR Code Generation in Java: From Simple Tokens to Custom Logos

Selected Java Interview Questions

Oct 10, 2025 · Backend Development

How to Separate External and Internal Authentication in Spring Cloud Microservices

This article explains why authentication loops occur when external user tokens and internal service tokens are handled together in Spring Security, and provides a step‑by‑step solution using distinct headers, custom filters, and Feign interceptors to break the cycle.

JavaSpring SecurityToken Authentication

0 likes · 9 min read

How to Separate External and Internal Authentication in Spring Cloud Microservices

Selected Java Interview Questions

Oct 9, 2025 · Fundamentals

Master Git Undo: From Reset to Revert – A Complete Cheat Sheet & Survival Guide

Learn how to treat Git like a “undo” button with clear analogies, essential command tables for beginners, step‑by‑step real‑world scenarios, safety tips for local versus remote rollbacks, and advanced tricks such as force‑push safeguards, making version‑control mishaps a thing of the past.

Force Pushresetrevert

0 likes · 8 min read

Master Git Undo: From Reset to Revert – A Complete Cheat Sheet & Survival Guide

Selected Java Interview Questions

Oct 8, 2025 · Backend Development

Mastering GraalVM Native Image Reflection: The Ultimate Guide for Spring Boot 3

This comprehensive guide explains why reflection configuration is essential for GraalVM native compilation, details Spring Boot 3's reflection mechanisms, enumerates common pitfalls with concrete solutions, and presents best‑practice strategies and tooling to reliably build native images for Java back‑ends.

GraalVMJavaReflection Configuration

0 likes · 5 min read

Mastering GraalVM Native Image Reflection: The Ultimate Guide for Spring Boot 3