This article introduces Java's BigDecimal class, explains its purpose for high-precision arithmetic beyond double's limits, details constructors, common methods, formatting, comparison, and exception handling, and provides practical code examples and a utility class for accurate mathematical operations.
This article explains a subtle thread‑pool deadlock caused by parent‑child task interactions, demonstrates the issue with a reproducible demo, analyzes why the latch logic fails, and provides a practical solution of isolating thread pools to avoid false‑deadlock behavior in microservices.
In a project with two applications, a Tair bean defined via JavaConfig works in one app but fails in the other because Spring’s injection rules prioritize type over name, causing ambiguity; using explicit bean naming with XML, adding @Qualifier, or switching to @Resource resolves the issue.
This article introduces the fundamentals and key features of Remote Procedure Call (RPC), explores common use cases and popular frameworks, then walks through the design and implementation of a custom RPC system using Netty, covering protocol design, client‑server communication, serialization, encoding, decoding, and result handling.
This article examines Java string concatenation performance by comparing the '+' operator and StringBuilder in both simple and loop scenarios, presenting JUnit test results, bytecode analysis, and practical recommendations for choosing the most efficient approach.
This article analyzes the problems of scattered property configuration in SpringBoot projects, designs a database table to store configuration items, implements a configuration loader that injects database values into the Spring environment, and demonstrates testing and best‑practice considerations for a robust backend configuration solution.
MapStruct is a powerful Java annotation‑based mapper that outperforms BeanUtils by generating compile‑time mapping implementations without reflection, supporting simple, nested, collection, and custom mappings, dependency injection, constants, expressions, and error handling, making object‑DTO conversions efficient and maintainable in Spring Boot projects.
This article explains why manual property copying in layered Java applications is inefficient, compares runtime copiers like BeanUtils and BeanCopier, and demonstrates how MapStruct provides compile‑time, type‑safe, high‑performance bean mapping with support for deep copy, collection mapping, field ignoring, and Lombok integration.
This article explains the object pool design pattern, its working mechanism, step‑by‑step Java implementation using Apache Commons Pool, advantages and disadvantages, and real‑world scenarios such as web server connection pooling and game object management, helping developers improve performance and resource utilization.
This article explains how to convert a list of Java User objects into a Map using Stream's toMap collector, handling duplicate keys and null values with merge functions and Optional, and compares alternative approaches including manual HashMap population.
This article examines the detailed steps and timing of establishing a MySQL database connection using Java, measures the latency of the TCP handshake and authentication phases, and demonstrates why connection pooling is essential for high‑traffic web applications.
This article presents eight practical retry mechanisms for Java applications—including loop, recursion, HttpClient configuration, Spring Retry, Resilience4j, custom utilities, asynchronous thread‑pool retries, and message‑queue based retries—along with code examples, configuration snippets, and best‑practice guidelines to help developers handle transient network failures reliably.
This article explains the limitations of ThreadPoolExecutor, introduces the Fork/Join model and ForkJoinPool in Java, demonstrates how to implement custom RecursiveTask and RecursiveAction classes with code examples, discusses pool construction, task submission, work‑stealing, monitoring methods, performance testing, and cautions about using the common pool.
This article presents a comprehensive guide to Spring's core utility classes—including Assert, ObjectUtils, StringUtils, CollectionUtils, FileCopyUtils, ResourceUtils, StreamUtils, ReflectionUtils, and AopUtils—showing their purpose, typical use‑cases, and code examples, while also containing promotional material for related services.
This article introduces MyBatis-Mate, an official MyBatis‑Plus extension offering enterprise‑level capabilities such as dictionary binding, field encryption, data masking, dynamic DDL maintenance, sharding, multi‑datasource switching, performance logging, and data permission control, with detailed Spring Boot integration examples.
The article explains that Spring MVC controllers are singleton by default, which makes mutable instance fields unsafe for concurrent requests, demonstrates the issue with sample code, and shows how applying @Scope("prototype") or using ThreadLocal resolves the thread‑safety problem.
Using JMH, the author benchmarks Java's switch‑case against if‑else and finds switch executes in about 0.44 ns per operation versus 1.55 ns for if‑else, with the gap widening as the number of branches increases.
This article provides an in-depth overview of common backend interview topics, covering MySQL index structures and storage engines, Redis single‑threaded design and persistence mechanisms, Java transaction ACID properties, SpringBoot auto‑configuration principles, JVM memory regions, class loading, and garbage‑collection algorithms, all illustrated with code examples.
This guide explains why traditional Java timers fail in microservice clusters, introduces Spring Cloud Alibaba's SchedulerX module with high‑availability and lock features, and provides step‑by‑step Maven setup, configuration, and code examples for both Alibaba SchedulerX and the open‑source ShedLock approach.
This article investigates the time consumption of creating and closing a MySQL connection from a Java application, measuring each network and protocol step with Wireshark and code examples, and demonstrates why connection pooling is essential for high‑traffic web services.
This article reveals five advanced Java tricks—using Unicode escapes in comments, over‑complicating simple logic with bitwise shifts, tampering with Boolean.TRUE via reflection, forcing both branches of an if‑else to run, and leveraging the Unsafe class for low‑level memory manipulation—to deliberately make code hard to understand.
This article summarizes the common pitfalls, monitoring techniques, configuration guidelines, naming conventions, and practical code examples for safely using Java ThreadPoolExecutor, helping developers avoid OOM, deadlocks, and performance issues while optimizing thread‑pool usage.
The article explains how sorting a List while iterating over it in Java can cause a ConcurrentModificationException, describes the fast‑fail mechanism of iterators, shows the root cause in nested method calls, and provides a safe fix using a copied list.
This article explains how to create a unified SpringBoot utility class that builds hierarchical structures such as multi‑level menus, comments, departments, and categories, discusses database design choices like the optional tree_path field, provides a detailed ITreeNode interface, implementation of TreeNodeUtil with code examples, and demonstrates testing and filtering scenarios.
This article explains Java's lock escalation process—covering biased, lightweight, and heavyweight locks—their underlying mechanisms, performance benefits, and the conditions under which each lock type is applied in multithreaded applications.
This article implements seven different HashMap traversal techniques in Java, benchmarks each with JMH, and shows that lambda‑based iteration and entrySet loops are the fastest, followed by Streams, while keySet‑based loops lag behind.
The article discusses Baidu’s new autonomous‑driving service “Robo Fast Run,” its potential impact on ride‑hailing jobs, the technical challenges involved, and provides detailed guidance on the qualifications and learning paths for engineers seeking positions in Baidu’s intelligent‑driving divisions.
Although many claim that using try‑catch in Java severely degrades performance, this article examines JVM exception handling, bytecode, and JIT optimizations, presents detailed test code and results under interpretation and compilation modes, and concludes that try‑catch has negligible impact when no exception occurs.
This article examines nine design patterns employed within MyBatis—Builder, Factory, Singleton, Proxy, Decorator, Adapter, Composite, Template Method, and Iterator—detailing their roles, source code examples, and how they facilitate configuration parsing, SQL execution, and caching in the framework.
This article reviews outdated Java technologies—JSP, Struts, Hibernate, and others—explaining why they are no longer essential for modern backend development and offering clear guidance on which skills to prioritize or abandon.
This guide explains how to implement an online user counting feature using Redis sorted sets, covering user identification methods, the essential zadd, zrangeByScore, zremrangeByScore, and zrem commands, along with code examples and a concise summary of the overall approach.
This article explains why excessive if‑else statements hurt Spring Boot code and presents six practical techniques—including strategy pattern, enums, polymorphism, lambda expressions, command pattern, and guard clauses—along with complete Java examples to make your backend more modular, readable, and maintainable.
Java thread pools efficiently manage and reuse threads by applying a producer‑consumer model, transitioning through RUNNING, SHUTDOWN, STOP, and TERMINATED states, handling task queues, and employing configurable rejection policies such as Abort, CallerRuns, Discard, and DiscardOldest, while improving performance, resource utilization, and stability across web servers, asynchronous processing, and other concurrent workloads, distinct from connection pools which manage database connections.
Covering workflow history, this article explains BPMN standards, outlines core modeling concepts, and demonstrates a practical SmartEngine integration that deploys BPMN 2.0 XML, highlights visual execution benefits, notes limitations in error handling and concurrency, and advises its use for moderately complex, frequently changing processes.
This guide presents ten practical strategies—including IDE selection, static analysis tools, unit testing, code reviews, and learning from others' post‑mortems—to help developers dramatically reduce bugs, improve code quality, and increase overall productivity.
This article provides a step‑by‑step guide on combining Spring Boot with the open‑source XXL‑Job platform, covering its features, comparison with other schedulers, configuration of the admin console and executor, code examples, @XxlJob annotation parameters, and best practices for reliable distributed task management.
This article presents a detailed overview of Spring's utility classes, covering assertion helpers, object and collection utilities, file and resource I/O methods, as well as reflection and AOP tools, complete with code examples for each feature.
This article outlines a business approval workflow where a commercial user adds a company and an administrator reviews it, and details the backend implementation using Java, IKAnalyzer for tokenization, MySQL regex and full‑text search for fuzzy matching, and code examples.
Jpom is a lightweight, low‑intrusion Java‑based tool that streamlines online building, automatic deployment, daily operations, and project monitoring, offering features like node management, SSH terminal, Docker handling, and easy installation, making it suitable for individuals and small enterprises.
This article explains how to handle massive MySQL export operations by introducing a fixed‑size FIFO queue, detailing the Java classes ExportQueue, AbstractExport, and ExportImpl, and showing a test controller that demonstrates queue limits, concurrency handling, and future considerations.
This article explains the concept of plugin‑based development, outlines its benefits such as modular decoupling and extensibility, and provides detailed Java implementations using ServiceLoader, custom configuration loading, and Spring Boot’s spring.factories mechanism with complete code examples and practical deployment steps.
Jpom is a simple, low‑intrusion Java‑based platform that provides online project building, automatic deployment, daily operations, and monitoring features, offering node management, SSH terminal, Docker handling, and a one‑click installation process suitable for individuals and small enterprises.
This article details a month‑long investigation and step‑by‑step tuning of a Java server's JVM parameters, memory‑leak fixes, and metaspace adjustments that reduced FullGC from dozens of times daily to a single occurrence every ten days while improving overall throughput.
The article critiques overly complex Spring Boot controllers filled with repetitive validation and business logic, demonstrates cleaner implementations using @Valid, Assert, and global exception handling, and provides practical code examples and guidelines for building maintainable backend controllers.
This guide explains how to set up JDBC drivers, construct connection URLs, use PreparedStatement instead of Statement, iterate ResultSet safely, manage resources with try‑with‑resources, handle transactions, employ connection pools, and properly process SQLExceptions for robust Java database applications.
This article explains how to secure OpenAPI interfaces by using globally unique AppId/AppSecret pairs, SHA‑256 and RSA signatures, timestamp and nonce validation, caching, rate‑limiting, parameter validation, and encryption algorithms, providing complete client‑server implementation examples in Java.
This article demonstrates how to insert 300,000 rows into a MySQL table using MyBatis and JDBC, compares direct batch insertion, row‑by‑row insertion, and optimized batch strategies, and provides performance measurements and practical tips for efficient large‑scale data loading.
This article explains how to use IntelliJ IDEA's advanced debugging features, including conditional breakpoints and the evaluate expression tool, with step‑by‑step instructions, practical code examples, and tips for efficiently locating and fixing Java runtime errors.
James Gosling, the Canadian creator of Java, announced his retirement after a five‑decade career that spanned IBM, Sun, Oracle, Google, Liquid Robotics and Amazon, highlighted by pioneering the Java language and virtual machine, earning prestigious awards and widespread admiration from the developer community.
This article compares popular Java etcd client libraries, evaluates their features, performance, and suitability, and provides a hands‑on tutorial using jetcd with Maven dependencies, code examples for watching and reading keys, and discusses runtime considerations such as thread handling.
This article walks through the sixteen JDK 14 JEPs, focusing on JEP 305’s instanceof pattern matching, JEP 361’s switch expressions, and JEP 368’s text blocks, providing design motivations, code comparisons, step‑by‑step usage, and practical tips for modern Java development.
The article explains why a NullPointerException occurs when a null String is used in a switch statement, detailing the underlying equals() and hashCode() calls, the required preconditions, and how Java compiles String switches, supplemented with illustrative code examples.
This article explains the drawbacks of using Spring Boot's @Value for configuration injection, demonstrates how @ConfigurationProperties provides a cleaner, maintainable alternative, and shows how to add validation with @Validated and standard bean validation annotations.
The guide demonstrates how to build a front‑end/back‑end separated captcha login using Spring Boot, Kaptcha and Redis, showing Redis‑based captcha storage with a unique key, Base64 image delivery, and verification logic that replaces traditional session‑based approaches.
This article demonstrates how to use the Template Method, Factory Method, and Strategy patterns in a Java Spring e‑commerce fulfillment system to clearly separate channel‑specific order handling, improve code maintainability, and enable rapid addition of new order types.
PowerJob is a Java‑based, enterprise‑grade distributed task scheduling platform offering a web UI, multiple scheduling strategies (CRON, fixed rate, delay, API), diverse execution modes, workflow support, and high‑availability, with detailed installation steps via Docker or JAR, configuration guidance, and sample code.
The article explains the concept of a dynamic thread pool, identifies common pain points such as invisible runtime status, hard‑to‑trace rejections, and slow parameter tuning, and presents a comprehensive solution that includes monitoring, alerting, automatic stack dumping, and live parameter refresh for Java backend services.
This article explains the evolution from traditional cookie‑session authentication to token‑based JWT, detailing its structure, security mechanisms, implementation steps, advantages, limitations, and practical Java code examples, while also comparing it with modern authentication challenges in web and mobile environments.
This article explains how to standardize API responses in a micro‑service architecture by defining a JSON result format with code, message, and data fields, using HTTP‑like status code ranges, and automatically wrapping controller outputs with a custom @ResponseResult annotation and Spring's ResponseBodyAdvice.
The June 2024 VS Code for Java update introduces enhanced project settings with new compiler, Maven, and formatter tabs, easier access via the status bar, test coverage improvements, Gradle Build Server projects, Spring feature upgrades including @DependsOn support and Spring Boot 3.3 compatibility, and new extension packs for Java development.
This guide explains how to implement data permission control in MyBatis-Plus by creating a custom annotation, an interceptor that modifies SQL before execution, a handler that builds WHERE clauses based on user roles, and how to register the interceptor in the MyBatis-Plus plugin, covering both basic and advanced versions.
This article introduces the Java Topology Suite (JTS), explains its core geometry models, WKT format, spatial relations, and operations, and demonstrates how to efficiently determine whether a point lies within service coverage polygons using MBR filtering, spatial indexes such as R‑tree and Quadtree, and geometry repair techniques.
James Gosling, the creator of Java, has announced his retirement, prompting a look back at his life, the birth of Java from the Green project, its evolution, and his post‑Sun career moves through Oracle, Google, a robotics startup, and finally AWS.
This article describes a backend solution for a company approval workflow that extracts key information from company names, tokenizes them using IKAnalyzer, applies MySQL REGEXP for fuzzy matching, and sorts results by match degree, complete with code examples and deployment tips.
This article explains the five SOLID design principles—SRP, OCP, LSP, ISP, and DIP—detailing their definitions, common violations, and Java code examples that demonstrate how to refactor classes for better modularity, extensibility, and maintainability.
The article explains AutoMQ's memory‑cache architecture, compares LogCache and BlockCache designs, analyzes Netty's internal and external memory fragmentation caused by the Buddy and PageRun/PoolSubpage allocators, and presents mitigation techniques such as ByteBufSeqAlloc to reduce OOM risks.
This article introduces Lock4j, a versatile Java distributed‑lock component supporting RedisTemplate, Redisson and Zookeeper, explains its key features, shows how to add dependencies and configure Redis, details the @Lock4j annotation attributes, provides simple and advanced usage examples with code snippets, and demonstrates custom executors, key builders, failure strategies, and manual lock handling.
This article demonstrates how to leverage Spring's TransactionSynchronizationManager to detect active transactions and register synchronization callbacks that asynchronously push payment‑ledger messages to Kafka only after the transaction successfully commits, ensuring data consistency and minimal impact on the main business flow.
This article walks through the complete troubleshooting process for a non‑functional logback‑spring.xml in a Spring Boot application, covering background, configuration steps, common pitfalls such as variable resolution and dependency conflicts, remote debugging techniques, and final recommendations to ensure proper log output.
This comprehensive guide walks you through Shiro's core concepts, authentication and authorization mechanisms, various realm implementations, session management, distributed session handling with Redis, caching strategies, and step‑by‑step integration of CAS single sign‑on using SpringBoot and pac4j, complete with code samples.
This article presents a real‑world case of optimizing a high‑concurrency transaction‑statistics API, detailing diagnosis of a 30‑second latency, SQL refactoring with array_agg and unnest, Java‑level improvements, and Caffeine caching, while also sharing promotional offers for ChatGPT services and a developer community.
This guide explains how to enable detailed G1 GC logging in Java, interprets both Minor (YGC) and Full GC log entries, breaks down heap size changes, worker threads, pause times, and points to the GCEasy analysis tool for deeper insight.
This article explains the fundamentals of symmetric and asymmetric encryption, how digital signatures and HTTPS work with certificate authorities, and demonstrates a practical implementation of secure URL encryption, key exchange, and request validation using custom Spring Cloud Gateway filters written in Java.
This article explains how to implement distributed locks using Redis, starting with a simple SETNX approach, identifying its shortcomings, and then presenting solutions such as thread‑identifiers, Lua scripts for atomicity, handling TTL with watchdogs, the RedLock algorithm, and practical usage via the Redisson Java client.
This article provides a step‑by‑step guide for Java engineers on building a Retrieval‑Augmented Generation (RAG) application using the LangChain4j framework, covering RAG fundamentals, environment setup, Maven integration, document loading, splitting, embedding with OpenAI, vector store management with Chroma, and prompt‑based LLM interaction.
This article explains how to implement distributed locks using Redis, starting with a basic SETNX approach, identifying its shortcomings, and then presenting robust solutions such as identifier‑based unlocking, Lua scripts for atomicity, the RedLock algorithm, and Redisson’s advanced features including a watchdog mechanism.
This article explains how to design a unified API response format for backend services, covering JSON structure, status code conventions, message handling, data payload, a Result wrapper class, controller simplifications, custom annotations, interceptors, and global exception handling to achieve clean and maintainable code.
This article explains how to replace Spring Boot's default embedded Tomcat with the high‑performance Undertow server, detailing Undertow's features, providing Maven dependency changes, showing configuration steps, and presenting benchmark results that compare QPS and memory usage, concluding that Undertow is preferable for high‑concurrency Java backend applications.
This article explains how to protect sensitive database credentials in SpringBoot applications by encrypting passwords in configuration files, leveraging Jasypt and a custom BeanFactoryPostProcessor to transparently decrypt values at runtime.
This article explains Java Metaspace and metadata GC thresholds, compares PermGen with Metaspace, and provides detailed JVM flag configurations—including size settings and compressed pointer options—to help developers optimize memory usage and garbage‑collection performance.
This article introduces Java 8 Stream API, explaining its declarative approach to processing collections, and demonstrates common operations such as filter, map, sorted, forEach, collect, statistics, and parallelStream with a PO class example, while also including full source code and brief promotional notes.
Learn how to enforce data permission rules in Java applications by using MyBatis mapper annotations, ThreadLocal context propagation, and custom MyBatis interceptors that modify SQL via Druid's AST parser, ensuring minimal intrusion to existing business logic.
This article explains the motivation behind creating the Easy-Query ORM for Java, demonstrates its fluent query capabilities—including single‑record, list, pagination, joins, sub‑queries, group‑by, native SQL and dynamic condition features—provides extensive code examples, and shares repository links for further exploration.
The latest TIOBE index shows Java falling out of the top three for the first time, C# overtaking it with a rapid market‑share gain, and Kotlin climbing back into the top twenty, while a detailed list of other languages and historical charts illustrate broader programming language trends.
This tutorial demonstrates how to set up a simple MySQL database, create a Spring Boot project, add Mybatis-Plus dependencies, install the MybatisX plugin, configure the connection, generate entity, mapper, service, and controller code, and verify the integration with a sample REST endpoint.
This article presents a comprehensive guide to improving Java backend performance by using parallel processing with CompletableFuture, minimizing transaction scope, applying effective caching strategies, configuring thread pools, reducing object creation, and employing various concurrency controls such as volatile, CAS, and read‑write locks.
This article explains why a Java thread pool with many waiting threads does not release resources, how calling shutdown or shutdownNow interrupts idle workers, how the ThreadPoolExecutor internals handle interruptions, and why proper shutdown is essential to allow both threads and the pool itself to be garbage‑collected.
This article explains the concept of request debouncing, outlines ideal debounce component characteristics, identifies which API endpoints need debouncing, and provides detailed Java implementations using shared Redis cache and Redisson distributed locks, including custom annotations, key generation, and practical testing results.
This article explains the TCP packet fragmentation and aggregation problems, introduces Netty's various decoder mechanisms such as FixedLengthFrameDecoder, LineBasedFrameDecoder, DelimiterBasedFrameDecoder, LengthFieldPrepender, and LengthFieldBasedFrameDecoder, and provides detailed configuration examples and code snippets for implementing robust TCP protocols.
This article demonstrates how to define a simple Calculator interface, provide both annotation‑based and reflection‑based implementations, and dynamically hot‑deploy user‑supplied JAR files by loading them with URLClassLoader, registering Spring beans, and handling bean removal on JAR deletion.
This article explains how to design a clean Controller layer in Spring Boot, introduces a unified response format with Result and ResponseBodyAdvice, demonstrates parameter validation using JSR‑303 and Spring Validation, and shows custom validation annotations and global exception handling to keep controller code concise and maintainable.
This article details a step‑by‑step investigation of a JSF thread‑pool exhaustion error that occurred when upgrading the Redis version of JD's internal R2M distributed cache, analyzing stack traces, lock contention, ForkJoinPool behavior, and the eventual remediation steps.
The Java Module System (Project Jigsaw) introduced in Java 9 defines uniquely named modules with descriptors that declare dependencies, exported and opened packages, and services, enabling clear dependency management, smaller custom runtimes, stronger encapsulation, improved performance, security, and easier maintenance, while supporting migration strategies and best‑practice guidelines.
This article explains the core architecture of Spring Security 6.x, detailing how a chain of servlet Filters implements authentication and authorization, the role of DelegatingFilterProxy, SecurityFilterChain, and the extensible components such as AuthenticationManager, UserDetailsService, and PasswordEncoder.
This article demonstrates how to insert 300,000 rows into a MySQL table efficiently by defining a User entity, configuring MyBatis and JDBC, comparing direct batch insertion, row‑by‑row insertion, and optimized batch strategies with configurable batch sizes and wait times, and provides performance results and best‑practice recommendations.
This article explains how to embed Lua scripts in Java applications with LuaJ, how to call Java code from Lua using LuaJava, and demonstrates dynamic extension, script auto‑upgrade, and bidirectional interaction through comprehensive code examples and detailed explanations.
This tutorial explains how to globally enforce data‑permission filtering in MyBatis‑Plus by creating a custom @UserDataPermission annotation, implementing an InnerInterceptor that modifies SQL WHERE clauses based on user roles, and configuring the interceptor within the MyBatis‑Plus plugin system.
The article explains the concept of dynamic thread pools, analyzes common pain points such as invisible runtime status, hard‑to‑locate rejections, and slow parameter tuning, and presents a comprehensive solution that includes monitoring, alerting, automatic stack tracing, and on‑the‑fly parameter refresh using Java code.
Learn how to use Maven Archetype to create standardized project skeletons, customize templates, generate and share archetypes, and integrate them into IDEs, streamlining Java project initialization, reducing manual setup errors, and improving development efficiency across teams.
This article walks through Java 17’s most useful language upgrades—including text blocks, enhanced NullPointerException messages, records, switch expressions, private interface methods, pattern matching, collection factories, Stream API extensions, the new HttpClient, JShell, direct file execution, and ZGC—showing why upgrading from Java 8 can boost code clarity and productivity.
