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How to improve performance of a Java application?

ImprovingtheperformanceofaJavaapplicationinvolvesacombinationofcodeoptimization,efficientresourcemanagement,properuseofJVMfeatures,andarchitecturalbestpractices.Herearekeyareastofocuson:1.OptimizeCodeandAlgorithmsIneffic

Aug 25, 2025 am 06:34 AM

How to Manage Transactionality in a Java Spring Application

Use@Transactionalattheservicelayertowrapbusinessunitsofworkinvolvingmultipleoperations.2.UnderstandpropagationbehaviorslikeREQUIREDandREQUIRES_NEWtocontroltransactioncontext.3.ConfigurerollbackForornoRollbackFortomanagetransactionrollbackoncheckedors

Aug 25, 2025 am 06:32 AM

Parsing and Generating JSON in Java with Jackson and Gson

Jackson and Gson are the two mainstream libraries for processing JSON in Java. 1. Jackson has stronger performance and rich features, suitable for high-concurrency backend and Spring integration, and supports streaming processing and multiple annotations; 2. Gson is simple and easy to use, does not require too much configuration, suitable for Android and lightweight projects, and is friendly to generic and null value processing; 3. Selection suggestions: Jackson is used in Spring environment, Gson is used in simple projects or Android; 4. Common points of attention: no parameter constructor is required, private field access is supported, date format is paid attention to and unknown field processing. Selecting the right library according to project needs can improve development efficiency and performance.

Aug 25, 2025 am 05:40 AM

What is JSP in Java?

JSP,orJavaServerPages,isaJavawebtechnologythatenablesdeveloperstocreatedynamicwebcontentbyembeddingJavacodewithinHTML,allowingfortheseamlessintegrationofserver-sidelogicandpresentation;whenauserrequestsaJSPpage,thewebserverautomaticallyconvertsitinto

Aug 25, 2025 am 05:24 AM

What are the best practices for handling null values in Java?

Return empty collection, Optional or default value instead of null; 2. Use Optional as the return type that may have no results; 3. Verify parameters with Objects.requireNonNull() and cooperate with @NonNull and other annotations; 4. Use secure navigation or Optional chains to avoid nested empty checks when necessary; 5. Reduce null fields through initialization and immutable objects; 6. Use static analysis tools to combine annotations to discover null problems in advance; 7. Avoid abuse of null and replace them with meaningful default values; Summary: APIs that make null rare and explicit should be designed to handle them as soon as possible, fail quickly, and use tools to avoid runtime exceptions.

Aug 25, 2025 am 05:18 AM

Client remotely executes server-side GUI applications: Download and start tutorial

This tutorial details the complete process of how a client downloads and runs a GUI application locally from the server. Through Java code examples, we will learn how to use URL and file operations to download JAR packages and use ProcessBuilder to launch the GUI application in the client environment, while providing important security and version management considerations.

Aug 25, 2025 am 05:15 AM

What does the static keyword signify in Java?

StaticinJavabelongstotheclass,notinstances,andenablessharingacrossallobjectswithoutinstantiation.1.Staticvariablesaresharedamongallinstances,withonlyonecopyexisting,suchasstaticintcountinaCounterclassthatincrementswitheachobjectcreation.2.Staticmetho

Aug 25, 2025 am 04:41 AM

java static

Building Event-Driven Systems in Java with Apache Kafka

To build an event-driven system using Java and ApacheKafka, you must first master the core concept of Kafka and implement producers and consumers in steps. 1. Understand the role of topics, partitions, producers, consumers, consumer groups and Brokers to achieve service decoupling. 2. Introduce kafka-clients dependencies in Java projects, write producer code to send events to specified topics, such as user login messages. 3. Create consumer subscription topics, get messages through polling and process business logic, and support horizontal scaling. 4. Follow best practices: Use SchemaRegistry to manage event structure, ensure consumer idempotence, process failed messages to dead letter queues, monitor consumption lag, and reasonably design partitions

Aug 25, 2025 am 03:56 AM

Spring Data JPA projection: efficient query and partial data mapping

This article explores in-depth how to use Spring Data JPA's Projections functionality in Spring Boot applications to efficiently select specific fields from the database and map to custom interfaces or DTO objects instead of complete entity classes. This solves the ConversionFailedException problem that occurs when directly mapping part of the query results (such as Object[]) to an entity, thereby optimizing the performance and flexibility of data retrieval.

Aug 25, 2025 am 03:36 AM

The Difference Between `String`, `StringBuilder`, and `StringBuffer` in Java

Stringisimmutableandthread-safe,makingitsuitableforconstanttextandscenariosrequiringnomodification;2.StringBuilderismutableandnotthread-safe,offeringhighperformanceforsingle-threadedstringmanipulations;3.StringBufferismutableandthread-safeduetosynchr

Aug 25, 2025 am 03:06 AM

java string

How to use constructors in Java

Java constructor is a special method used to initialize objects. It must be the same name as the class name and has no return type; 1. The constructor is automatically called when the object is created and is used to set the field initial value; 2. It is divided into default constructor (no parameters, automatically provided by Java), custom parameterless constructor and parameterized constructor; 3. It supports constructor overloading, allowing multiple constructors with different parameter lists in the same class; 4. The constructor chain call can be implemented through this() to reduce duplicate code; 5. After defining any constructor, Java no longer provides the default parameterless constructor; 6. The constructor can be used to verify input, ensure the validity of the object state, and improve the robustness of the class. Correct use of constructors ensures that the object is always in a consistent initial state

Aug 25, 2025 am 02:33 AM

What is the finally block in Java?

ThefinallyblockinJavaalwaysexecutesafterthetry-catchblock,regardlessofwhetheranexceptionoccursorareturnstatementisencountered,makingitidealforcleanuptaskslikeclosingfilesorreleasingresources;itrunsevenifanexceptionisthrownandnotcaught,orifamethodexit

Aug 25, 2025 am 01:50 AM

What is JDBC in Java?

JDBC,orJavaDatabaseConnectivity,isastandardAPIthatenablesJavaapplicationstointeractwithrelationaldatabaseslikeMySQL,PostgreSQL,Oracle,andSQLServerbyactingasabridgebetweenthem.ThekeycomponentsincludeDriverManagerformanagingdatabasedriversandestablishi

Aug 24, 2025 pm 03:04 PM

java jdbc

How to use a List in Java

ChooseArrayListformostusecasesduetobetterperformance,orLinkedListforfrequentinsertions/deletions;2.Addelementswithadd(),accesswithget(),andchecksizewithsize();3.Modifyelementsusingset()andremoveelementsviaremove()byindexorvalue,avoidinginvalidindexes

Aug 24, 2025 pm 02:00 PM