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Top 23 Java Open-Source Projects

  • GitHub repo JavaGuide

    「Java学习+面试指南」一份涵盖大部分 Java 程序员所需要掌握的核心知识。准备 Java 面试,首选 JavaGuide!

    Project mention: Top 10 Developer Trends, Sun Oct 11 2020 | dev.to | 2020-10-11

    Snailclimb / JavaGuide

  • GitHub repo Design Patterns

    Design patterns implemented in Java

    Project mention: At what level will MOOC free online course take you? | reddit.com/r/learnjava | 2021-05-07

    Followed by Design Patterns (Quick intro)

  • GitHub repo Spring Boot

    Spring Boot

    Project mention: Spring Boot Development Environment with Docker and VS Code | dev.to | 2021-05-03

    In a recent past, for Java projects - more specifically Spring Boot ones, I used to install sdkman and tried to arrange with the whole team to use the very same vendor and version of the JDK. Problem is, it depends on human actions to work. And humans can fail.

  • GitHub repo Elasticsearch

    Free and Open, Distributed, RESTful Search Engine

    Project mention: Rolling over rolledup index | reddit.com/r/elasticsearch | 2021-04-27

    AFAIK the rollup API is currently being rewritten in order to integrate it into the index lifecycle management (ILM). See also https://github.com/elastic/elasticsearch/issues/42720 . Therefore in future rollup indexes will also have a lifecycle and be deleted after some time.

  • GitHub repo advanced-java

    😮 Core Interview Questions & Answers For Experienced Java(Backend) Developers | 互联网 Java 工程师进阶知识完全扫盲:涵盖高并发、分布式、高可用、微服务、海量数据处理等领域知识

    Project mention: Top 10 Developer Trends, Mon Oct 12 2020 | dev.to | 2020-10-12

    doocs / advanced-java

  • GitHub repo interviews

    Everything you need to know to get the job. (by kdn251)

    Project mention: Free Computer Science Resources with Interview Prep and much more... | dev.to | 2021-03-29


  • GitHub repo RxJava

    RxJava – Reactive Extensions for the JVM – a library for composing asynchronous and event-based programs using observable sequences for the Java VM.

    Project mention: MVVM Architecture On HarmonyOS Using Retrofit And RxJava | reddit.com/r/HuaweiDevelopers | 2021-03-29
  • GitHub repo Guava

    Google core libraries for Java

    Project mention: ReversibleCollection proposal | reddit.com/r/java | 2021-04-17

    There seems to be a focus on LinkedHashSet. The guava guys had a go at UniqueList instead what are yours thoughts on that?

  • GitHub repo OkHttp

    Square’s meticulous HTTP client for the JVM, Android, and GraalVM.

    Project mention: 60% of school apps are sending student data with third parties without consent | news.ycombinator.com | 2021-05-04
  • GitHub repo Retrofit

    A type-safe HTTP client for Android and the JVM

    Project mention: I made an app that helps you sync your clipboards between your Windows PC and your Android device. | reddit.com/r/Python | 2021-04-14

    * As android developer i suggest you use Retrofit for endpoint call.

  • GitHub repo Java

    All Algorithms implemented in Java

    Project mention: Any beginner-friendly tutorials on hashing +salting strings? | reddit.com/r/learnjava | 2021-03-27

    here you can use of the ciphers

  • GitHub repo MPAndroidChart

    A powerful 🚀 Android chart view / graph view library, supporting line- bar- pie- radar- bubble- and candlestick charts as well as scaling, panning and animations.

    Project mention: How to create bar chart from scratch? | reddit.com/r/androiddev | 2021-05-09

    Creating custom views like a chart is not what you sholud start learning with. To be honest, most of the time we're using libraries that provide ui things. We just custiomize things and rarely write everything from scratch. You should focus on other things like design patterns, core libraries, async code, ui components, design patterns and Android API in general. Look at this library https://github.com/PhilJay/MPAndroidChart , it should be pretty good.

  • GitHub repo Apache Spark

    Apache Spark - A unified analytics engine for large-scale data processing

    Project mention: Hi we have a stranege error while moving to spark 3.0.2 | reddit.com/r/apachespark | 2021-05-07

    Checking the code that seems to throw this error (here) this seems to hint at having some form of column name repeated. It may be an internal issue, and that you are reusing a name that is already present in one of the base tables, for instance. It's hard to know with the rewritten query you provide, since you may have rewritten it "correctly", also, the error could actually be propagated from some naming before, since this is a whole plan rewrite stage after all.

  • GitHub repo ZXing

    ZXing ("Zebra Crossing") barcode scanning library for Java, Android

    Project mention: Is there any way to use an object reference to fetch the object itself? | reddit.com/r/java | 2021-03-24

    Have a look at ZXing or QRGen.

  • GitHub repo leakcanary

    A memory leak detection library for Android.

    Project mention: I'm so bad at writing code , I don't even need proguard to make my code unreadable. Please guide me! | reddit.com/r/androiddev | 2021-04-17

    LeakCanary will help you find memory leaks in your code: https://square.github.io/leakcanary/

  • GitHub repo jadx

    Dex to Java decompiler

    Project mention: Analysis of ViaWallet | reddit.com/r/handshake | 2021-04-22

    Used: mitmproxy/Burp Suite to understand how the api works, and jadx to try to get readable decompiled source code once I knew what to look for and general idea of what to expect/how it works.

  • GitHub repo Arthas

    Alibaba Java Diagnostic Tool Arthas/Alibaba Java诊断利器Arthas

  • GitHub repo fastjson

    A fast JSON parser/generator for Java.

    Project mention: Ask HN: Differences in Programming Style by Nationalities | news.ycombinator.com | 2021-04-19

    I first noticed a difference in national styles when I contributed a patch to fastjson, a JSON parser in Java from Alibaba.

    Take a look around the repo; it'll look odd to a western programmer. There is a lot of duplication. And the tests don't have names, they are numbered.


    This was several years ago. I did end up choosing it since it really was the fastest.

  • GitHub repo spring-boot-demo

    该项目已成功集成 actuator(监控)、admin(可视化监控)、logback(日志)、aopLog(通过AOP记录web请求日志)、统一异常处理(json级别和页面级别)、freemarker(模板引擎)、thymeleaf(模板引擎)、Beetl(模板引擎)、Enjoy(模板引擎)、JdbcTemplate(通用JDBC操作数据库)、JPA(强大的ORM框架)、mybatis(强大的ORM框架)、通用Mapper(快速操作Mybatis)、PageHelper(通用的Mybatis分页插件)、mybatis-plus(快速操作Mybatis)、BeetlSQL(强大的ORM框架)、upload(本地文件上传和七牛云文件上传)、redis(缓存)、ehcache(缓存)、email(发送各种类型邮件)、task(基础定时任务)、quartz(动态管理定时任务)、xxl-job(分布式定时任务)、swagger(API接口管理测试)、security(基于RBAC的动态权限认证)、SpringSession(Session共享)、Zookeeper(结合AOP实现分布式锁)、Ra

    Project mention: Top 10 Developer Trends, Sun Oct 11 2020 | dev.to | 2020-10-11

    xkcoding / spring-boot-demo

  • GitHub repo Selenium WebDriver

    A browser automation framework and ecosystem.

    Project mention: No longer working: Selenium options.add_argument("user-data-dir=selenium") | reddit.com/r/webscraping | 2021-05-03

    Are you sure you don't mean add_argument("--user-data-dir=...") like the rest of them?

  • GitHub repo libGDX

    Desktop/Android/HTML5/iOS Java game development framework

    Project mention: Box2d velocity depending on frame rate. | reddit.com/r/libgdx | 2021-05-09

    Is your stepping not based on delta time? See the example at https://github.com/libgdx/libgdx/wiki/box2d#stepping-the-simulation

  • GitHub repo JHipster

    JHipster is a development platform to quickly generate, develop, & deploy modern web applications & microservice architectures.

    Project mention: Is spring / springboot suitable for monoliths or is mainly designed for microservices? | reddit.com/r/java | 2021-04-29

    Definitely, maybe you should check JHipster project. https://www.jhipster.tech/

  • GitHub repo Exoplayer

    An extensible media player for Android

    Project mention: Plex for Android v8.14.0 Released | reddit.com/r/PleX | 2021-03-11

    As long as you provide a way to re-link a LGPL library upon request (statically linked or not), it's fine. GPL, AFAIK, won't allow this. Though honestly I'm very surprised the Plex clients are no longer open source. It's incredibly unfortunate. People would jump to improve it because we are tired of waiting. This was done with ExoPlayer, yet now it seems even when ExoPlayer supports the feature entirely, Plex on android will lag behind for several years.

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020). The latest post mention was on 2021-05-09.


What are some of the best open-source Java projects? This list will help you:

Project Stars
1 JavaGuide 102,868
2 Design Patterns 65,710
3 Spring Boot 54,928
4 Elasticsearch 54,745
5 advanced-java 53,831
6 interviews 51,175
7 RxJava 44,556
8 Guava 41,005
9 OkHttp 39,926
10 Retrofit 37,999
11 Java 36,941
12 MPAndroidChart 33,250
13 Apache Spark 29,532
14 ZXing 27,646
15 leakcanary 26,103
16 jadx 25,855
17 Arthas 25,647
18 fastjson 23,323
19 spring-boot-demo 21,699
20 Selenium WebDriver 20,709
21 libGDX 18,381
22 JHipster 18,348
23 Exoplayer 17,630