Ask HN: What is a modern Java environment?
Hello,
I used Java a very long time ago, like 1.6, and I'm wondering what using Java at work in ~web backend looks like today.
What elements of your stack would you consider most important? Do most projects lean heavily on Spring Boot or something else? Which IDE? Pointers to refreshers or concise introductions you might give a new hire would be handy too. I'll chime in my opinion: Java is getting something right that I don't see much elsewhere: Dependency Injection. Combine this with a mocking framework and you can write _actual_ isolated unit tests for every single part of your stack. We're fans of CDI, it's a more polished Spring framework without the legacy weight. We're developing in Quarkus, MicroProfile, and bigger monoliths in Apache TomEE. We use ActiveMQ extensively for scaling. ( And I mean extensively... on a modest 512m server, we can push several thousand messages/s reliably to a _lot_ of topics and queues, all with delivered-exactly-once guarantees) We avoid the fanfare of Docker, as really it's not needed for Java apps; they're somewhat self-contained anyway and it created more problems than it solved. For true isolation, we use systemd to create cgroups and chroots and prevent application escapes. For deployment, apps are one-jar'd down to a single executable, then packaged up in a .deb using the jdeb maven plugin. We stick with the unix philosohpy of using /etc/default for env variables that help the app locate their database or LDAP cluster. I've been a developer over a decade, never touched the JVM because I always figured it was bloated Enterprise garbage. I did a project using GraalVM's polyglot abilities and needed an API. Tried Spring, Micronaut, Helidon, Ktor and Quarkus. Quarkus is the best web framework I've ever used, in any language. Can't go back now. It's so well-architected that I was able to contribute an extension for Scala 3 support within a month, and the Redhat employees have answered every question + issue I've raised. Being built on top of the Microfile spec and using Vert.x is a hell of a combo. Vert.x is the best thing since sliced bread too. Can't recommend Quarkus enough, whether you write Java or Kotlin or Scala (I'm a big Kotlin fan myself). Just had a look at your scala 3 extension, it's really nice. Does it support hot code reload like you would get in quarkus dev mode with java? Yes, that's correct =) Admittedly the install instructions for Gradle are a bit dated. Gradle 7.4 shipped with Scala 3 support. While you are correct that DI is very good in java, DI is needed because of heavy reliance on OOP (i.e, in order to create an instance of an object, you have to lock in functionality with a dependency before you can run that functionality). If you use a language that doesn't require OOP, you can do the same isolated unit tests without DI. I want to expand on what you said: It's more than just OOP, or not necessarily OOP in general that needs this type of DI and IOC. It's a specific category of OO architecture, where effects and state are buried under domain logic and information processing (via DI). If you keep that part data oriented and pragmatically functional, then you get a very testable core. Meaning no mocks, stubbing setup/tear-down (...) are required. No additional interfaces have to be specified that you didn't need in the first place. Tests are way simpler this way. You can still use objects, interfaces and composition etc. for domain logic and information processing if you want. Point is you lift state and effects up, so this stuff happens at the edge of your program that calls into a simpler core. > Java is getting something right that I don't see much elsewhere: Dependency Injection. Combine this with a mocking framework and you can write _actual_ isolated unit tests for every single part of your stack Since dotnet core started this has been front and center in C#. So there are other stacks doing this. Very happy to see this. I think it's a great pattern. It pushes functional concepts into code and stuff like state management into the runtime. I prefer to skip the mocking frameworks and rely on Interfaces instead. My unit tests create anonymous inner classes that are passed to the constructors. If it takes too much effort to write that anonymous inner class, then the Interface may be too big and need broken up. Or maybe you're hiding too much state and need to rethink the API. Containerization is great. It allows you to write all the infrastructure for you Java app as code and then just simply type 'docker-compose up' to get it running (or whatever your orchestrator). This makes it super portable. Just something to think about. I personally think the win's from Containerization are greater than the challenges. I admit we do miss that part. Instead for us it's `sudo apt -y install app-name` installing the app locally isn't as sustainable. The data and configuration for test environments gets scattered across the system and is less reproducible for new comers. As changes are made to the test environment, developers have to then install/update/reconfigure manually. It becomes an nmo effort with less consistency and more error over the single line docker-compose up Don't disagree, but we just avoid writing stuff where you need to have 10+ apps running locally to run "an app". That itself isn't sustainable architecture, those should be one app in a monolith. That being said, to your point, we do have some inter-service dependencies that have to run separately. We haven't figured out a good balance yet, but it's the exception not the rule fortunately, and everyone "just knows" how to run an extra app in those extreme cases. do you have a 'sudo apt uninstall app-name' to clean everything up? Yes! In fact, an upgrade path too in the script. Sounds great as long as you either put work into multi OS compatibility or stick to the same OS. Depending on your situation that sounds like you have a good solution that's working and you're happy with. You don't necessarily need containers for that though? Containers offer a lot of advantages, portability, IaC, OS abstraction, common predictable environments, etc. I personally like them a lot but it's definitely not the only way to do things. The alternative would be hosted functions, like lambda, which is just running in someone else's containers. "something right that I don't see much elsewhere: Dependency Injection. Combine this with a mocking framework and you can write _actual_ isolated unit tests for every single part of your stack." It's exactly the same in the .NET space > We avoid the fanfare of Docker, as really it's not needed for Java apps; they're somewhat self-contained anyway and it created more problems than it solved. What does this mean? Because the code runs in a VM already, they are not concerned about isolating further. For example, if you're writing code in C++ targeting Linux, using Docker helps with reproducible builds and deploying on any hardware. But if you have a VM, there are less advantages. There still are some, of course, with orchestration etc if you want it. I guess I was implying that I don't view the benefits between the prior and the later as an onto mapping. Java apps have been "cloud ready" in a sense for about 20 years. JavaEE had a "WAR" or web archive file format that packaged an entire app up into a single file that could be deployed in an "Web Application Server". IBM wanted web servers to be mainframes, but for webapps. You could even deploy multiple apps in a single JVM, because the server would load each app in a separate classloader, meaning the apps were internally isolated from each other. The JVM even had an attempt at a cgroups like concept, called a Security Manager (that was abandoned, thank goodness), long before cgroups existed. Think WAR file = docker container. Now, a lot of complicated bits were inherited that didn't need to be there when they brought over the mainframe thinking into Java apps, but the WAR format was actually something kind of cool they got right. We in particular, take that WAR format, turn it into an executable, and we have a program that can execute on any hardware on any person's computer, with no pre-reqs except a JVM being installed. We test the _exact_ war file on a ARM RPI , developed on a Mac m1 or x86, and CI on a Linux x86. Alright what does this mean? Lets take a look at another language...say a PHP application.... which may require extension Unix utilities of certain versions installed on the host system. You may need a certain version of PCRE grep, a certain version of curl, etc. This theme carries over to multiple languages, your python or ruby implementation may not support the latest version of libressl, or it might not even support your ABI at all. Docker solves these problems gracefully, by providing a fully configured virtual operating system tuned for running exactly one app. The JVM... well doesn't need that, if written properly. Generally all the libs it uses are written in Java, they include all of their dependencies already, apps can be isolated with classloader boundaries (if that's your thing), you can download a single file and launch it if you use the "one-jar" technique. So yeah, Docker loses a lot of it's luster with Java. It's not that you _cant_ use it, but it you can solve all the problems it does otherwise. Long rambling explanation but there you go. I think it means that they like to install software and manage servers rather than renting a container cluster to host your app. The stack I've seen, used and liked at many clients is: Spring Boot, Kotlin, IntelliJ. Which of course means all the old discussions: Jetty/Tomcat/JBoss/GlassFish, GSON/Jackson, Hikari/C3PO/etc, etc are now mostly moot, since most just use the Boot defaults until they need something else.
Kinda nice, actually. Less bikeshedding, can get a project up and running without taking a stand on all these things. Most clients use maven, a few gradle, some used gradle and moved back when no one could understand their config. Gradle might get a second chance now that it can be written using kotlin. Yes. Perhaps to add to this, use a modern asynchronous IO framework. If you use Spring Boot, ignore some of the legacy stuff that still comes with it and make sure you use webflux with Kotlin co-routines. Also use Asynchronous IO for talking to your database, queues, etc. Kotlin makes all of this easy. Hibernate is something I tend to avoid for various reasons but apparently recent versions of that now also support asynchronous IO. And it is still very popular. If you feel more adventurous. Ktor is also quite nice and a lot more lightweight than spring. They have a pretty big 2.0 release coming up for that with a lot of nice improvements. Ktor is also a nice alternative for doing http clients. Kotlinx serialization is the way to for serialization; especially if you are interested in multiplatform. Spring supports that as well since a few releases. If you use Kotlin, stick with Gradle and use the kotlin scripting variety. Maven is very much a second class citizen in that ecosystem. It's supported (grudgingly) but not that actually that widely used. A lot of older Spring projects might still use it because they started out as maven/java projects and only later added Kotlin. However, if you start from scratch, just use gradle and take the path of the least amount of resistance. You'll have an easier time and essentially all of the Kotlin documentation assumes you use gradle. For things like kotlin multi-platform, maven is an afterthought. I'd be surprised it works at all actually for that. I really wouldn’t go the async way unless it was deemed absolutely necessary for maximal performance — it makes reasoning/debugging much harder with often not much gain. Also, if one can just wait a few years, loom will make many part of it obsolete - when blocking code will magically get non-blocking while it retains the readibility. I've had very few issues with that. Mostly the async code looks almost identical to the synchronous variant with Kotlin. There's a bit of a learning curve and it helps if you understand parallel and asynchronous programming a little. There is no magic with blocking vs. non blocking. Your IDE will tell you if you are doing it wrong. The fix is usually to have a co-routine context backed by a thread pool and schedule co-routines that block there. Loom won't make any of this obsolete. If anything, co-routines will probably be the most user friendly API to use Loom when it comes available. Loom is a pretty low level API and you probably should not use it directly and instead use something that uses that. Like Kotlin co-routines, which is designed as a high level API that can be backed by all sorts of asynchronous and parallel computing implementations/ Extension functions exist for webflux, rx-java, vert.x, thread pools and much more. Basically, it sits on top of these things. It also works on kotlin native, kotlin-js (in a browser and node-js) and in the JVM where the underlying platform of course provides very different implementations. For the end user, it works pretty much in the same way across these platforms. Loom will just be another low level backend for the co-routine API. It will likely give you some performance benefits if it's available and that's about it. Update the co-routine library, maybe fiddle a bit with your co-routine scope's and you'll be using Loom. I'd expect very little code changes would be needed when the time comes. Perhaps none at all actually (aside from bumping a version number). I find the big problem with async is the libraries, not necessarily the async piece itself. I looked at Webflux (Project Reactor)/RxJava/etc. years ago and discovered that the composable async components unexpectedly maintain state, and that's really the piece that makes it hard to reason about. I've since switched over to Scala + cats-effect. I found that to be a huge learning curve, but the payoff for me has been library support for easy-to-use and easy-to-understand concurrent and asynchronous programming. I cannot recommend it enough. I tried to keep my post very little opinionated, and just write what I've seen the last couple of years. While you have some good points in yours, it's not necessarily the best idea to go straight for these "hipper" things if one's trying to break into java dev. Then it's easier to start with the boring stuff everyone use, as that is what one most likely will encounter. As for Hibernate, I've seen a trend of using ORMs less and less. And if it's used, it's in a simple dao layer so that the rest of the application doesn't have to deal with how data is fetched. I don't consider synchronous programming as being legacy. For many projects synchronous programming can work just fine, and it lowers complexity. I wouldn't bother with async unless there's a solid reason. Most Java libraries assume a standard, synchronous model and Java threads are relatively cheap these days. There's no point in going against the grain. This is it. The irony is that the modern Java stack uses the JVM & classlib, but a different language. If you want to go full hipster, there is Micronaut (also Quarkus) and if you'd like to go a bit off-charts, there is Dropwizard. I don't think that they offer anything extra over SB though. Or for hipsters there's https://www.jhipster.tech/ One of my first PRs ever was to that project, back in 2013. Then it was a nice starter project, showing how one could move away from the clunky server side rendering frameworks at the time, instead using AngularJS on the frontend and having a backend. And also included a nice simple Spring setup, before Spring Boot existed. So pretty hip, and very lean. Since then it has.. evolved to something quite big, I feel, where one quickly end up with lots of unknown boilerplate in one's project. I mean, it's probably useful in its own way, almost like a Django alternative or something with batteries included. But not very hipster anymore. Can confirm this is my stack at a fortune 500 web/entertainment company. As someone who hasn't really touched the Java ecosystem since around the time of Java 7, where would you recommend starting? Pick up Kotlin first, then Spring Boot? Or the reverse? And is the free version of IntelliJ good enough? I noticed on the features list that Spring support wasn't listed Like with any language pick something you want to build and then build it and perhaps don't get too carried away with the level of ambition. Intellij Community edition is fine. It's what I use. Some of the spring support in the commercial edition is nice but I don't really miss it. If you have some old Java code, a good way to get started is converting some of that to Kotlin in intellij. You'll get familiar with the syntax that way and you can figure out the language as you go. Mostly things are a bit different but not that much. Nicer too. I remember my first afternoon of converting a few tests and then really liking what I saw. That's five years ago. If you are doing a greenfield project, I'd suggest starting with a simpler framework like ktor. Especially if you come from a node.js or go background. Ktor is very nice. No annotation magic, easy to understand, and you can write a simple http service in a few lines of code. There's nothing wrong with Spring Boot (I use it), but it's just a lot to wrap your head around and figure out. Even just deciding on which bits you should and shouldn't work involves a lot of decision making. It has a lot of legacy features at this point. * Use SDKMan for runtime and sdk management https://sdkman.io/ * Try to use Kotlin where allowed (Maybe unpopular and bad faith response given that you asked about Java, but I don't care -- kotlin's Java interop is way more seamless than Scala or Clojure to the point that its often not even noticable) https://kotlinlang.org/ * IntelliJ * Spring is pretty popular, I've seen a lot of people using Vertx * Square libraries like Okio, okhttp, retrofit, wire https://github.com/square * If you're not using spring, use Dagger for DI https://dagger.dev/dev-guide/ * Overlook netflix abandonware (another unpopular opinion, I'm sure) * Use gradle, not maven. Use kotlinscript as the config language, not groovy I'd suggest using koin instead of Dagger. Dagger is alright but mainly popular in the Android world where Koin is the main alternative. However, Koin is native to Kotlin and a kotlin multiplatform project. So you can use it on Android, server development, IOS native, kotlin-js, etc. Nice, I haven't seen this one. We've been using Dagger to get people off of runtime DI for migrating to serverless, but I'll take a look. I assume it's compile-time DI? Koin is a kotlin DSL. So no annotations, reflection, or compiler magic are needed. Basically it just instantiates things for you on demand and uses normal kotlin features like lambda functions, receiver objects, and property delegation. You can inject a property by defining it as a koin injected property: Spring has a similar kotlin bean dsl that was added a while ago that you can use as an alternative to annotation processing (which is much slower). It's not, it's a runtime service locator. In my experience it doesn't scale terribly well. Okio is very nice, and Okhttp is quite ergonoic, but I can't recommend Okhttp if true async is on the table (it's just blocking and threadpools under the covers). And Kotlin's coroutines are also "just blocking and threadpools under the covers", but people will still sing their praises. It's really not a killer for most people using it. Admittedly it's been awhile since I've written Java, so most of this is what I remember and what I've seen successful teams using -- got any links to a "true async" in Java? I was under the impression that all Java async work was backed by thread pools. Yes, anything that uses NIO / Netty / epoll / io_uring / etc. under the covers will do. There are several options--IIRC at least five choices are available, but these are the ones that come to mind: https://openjdk.java.net/jeps/321 https://github.com/AsyncHttpClient/async-http-client https://hc.apache.org/httpcomponents-client-5.1.x/examples-a... Thanks! I did a little research and it seems like there are some Kotlin coroutine to nio mappings (it looked like some were experimental though) and that OkHTTP is aiming to use coroutines, so I wonder if these will converge in the future. What wasn't clear to me was if the coroutine/nio mashup still used threadpools because coroutines do. > Try to use Kotlin where allowed If you want a slow build and code that is fun to write but hell to read, that is good advice. > Use kotlinscript as the config language Extremely slow, that is. I disagree that it's easier to write than read. I tend to think Kotlin is much easier to read than java but harder to write because it tries to enforce good Java patterns at a language level. I agree that these will slow down your build, but not significantly, and at the benefit of developer comfort to make changes. Incremental compilation largely erases these slowdowns. Extension methods? Aliases? Countless more features that are designed to make your code hard to read & understand. Build scripts are generally written once and executed hundreds or thousands of times. It makes far more sense to optimize their performance rather than ease of writing. It's okay to have a different opinion, but personally I'd never work at a place that did that. Java is already on thin ice and this is simply how I tolerate it and how I've seen successful java teams operate in cloud environments. If you are really seeing dramatic build times, I don't blame you for investigating them, but I'm not going to forgo years of DX improvements just because I heard on the internet one time that it's slower. I'm not going to keep arguing against your Kotlin vendetta, just don't use it, I don't care. Java is on thin ice? It's the most popular business language, for good reason. You seem to have some very odd opinions, but that's fine. Bit rude to call people other people their opinions a "vendetta", though. The reason I'm being terse with you and perhaps a bit rude is that you started this reply thread by insulting my opinions for no reason and then continued to reply with what I believe to be both bad faith readings of my comments and naturally argumentative. I know HN values skepticism, but honestly it's tiresome. Anyways, here's my clarifying my previous comment. Please keep in mind that I fully expect you to read this in bad faith, so I've added sarcasm overtly. Java, for me, personally, in my opinion, is on thin ice. I personally, in my opinion, would never work at a "Java shop" because in my opinion, personally, it conveys a disregard for technical suitability and individuality and supports the idea that engineers should be expendable. I believe, in my opinion, personally, that Java is, as you say, "popular" because it's forced on many workplaces by management. I don't think, in my opinion, personally, that it's a "bad" language, but its heavy use is not proportional to how "good" it is. I don't think my willingness to respond but refusal to be berated by an internet stranger is rude, and yes, I believe you have a vendetta, just like I have a vendetta against Java. If you have to use it, fine -- the above will insulate you from the really terrible things java does, in my opinion, personally. My real advice is don't use java, but see how that's a bad faith response? That's why I kept it to myself. So Java isn't on thin ice if it's used heavily. What do you want to hear? That you're right? Communication is a two way street, try treating it like one. "To be on thin ice" is an expression which means in a precarious or risky situation, but is commonly used in reference to personal regard or favor. !!!!!!YOU'RE RIGHT!!!! (congratulations!) Java is not at risk of falling out of use - it's a very heavily used language with lots of job opportunities. Congratulations again on being technically correct. If that's all you wanted stop reading. I'm saying that writing, maintaining and deploying Java in a manner that is fast, pleasant, sustainable, performant and desirable for developers is already at risk, in my opinion. As a developer, Java is *not* the best solution and taking away the niceties listed puts Java in a place where it is at risk of being unsuitable for the task. This isn't solely a fault of Java, some of this is simply better solutions for problems existing around Java. Java moved quite slowly for a long time and solutions filled that gap. I understand a business' desire to have a uniform programming language that they can hire for, but these days languages look very similar and polyglotism isn't that hard to find. Choosing the right language for the task is an engineering decision just like preserving language uniformity is. I don't think either is wrong, but the more people try to make Java a place that is worse than it's competitors, the more I'll favor choosing a different right language over preserving uniformity. I hope this helps clarify what I saw to be an extremely benign opinion to voice. Java is the COBOL of the 21st century, in both the best and worst sense. Java stacks will be running major companies long after everyone posting in HN today is dead and gone. I agree. Build process with Kotlin feels slower. And the many features in Kotlin tempt me to write "syntactically clever" code that is harder to read later than plain stupid Java. Still love some of them :) although Java is catching up. Along with the various other libraries and frameworks mentioned; * Testcontainers - seamless support for using Docker in integration tests [1] * Project Reactor - nice framework for reactive programming
[2] * Executable Jars - No need to deploy a War file to a servlet container anymore. Build an executable Jar with an embedded container. Spring Boot makes this very easy My company's product is primarily written in Java. It's a web based auth system, fwiw. I don't write too much code nowadays, but read a lot. From what I can see, here's the stack: * intellij for an ide (with tons of plugins) * prime MVC (https://github.com/prime-framework/prime-mvc) for the framework * mybatis for SQL/queries * java 17 I've also used dropwizard and spring. If it was a greenfield development with emphasis on developer productivity, I'd go with spring any day. Big dev community, tons of doco, a solution for any problem if you can find it. For backend frameworks, I'd look at Quarkus [1] or Micronaut [2]. Both are geared towards configuration, async processing and native compilation, along with a ton of options to integrate with external systems. For something a bit lighter weight, Vert.x [3] is a good option (Quarkus is based on it). [1] - https://quarkus.io/ [2] - https://micronaut.io/ [3] - https://vertx.io/ You'll need Java 1.8+, and Maven or Gradle for the toolchain (I prefer the former). Intellij is the best IDE but I get by with VSCode. There's no reason to use 10 years old version of Java. Use 17. True. I was just stating the minimum level. Here is what we use and I'd recommend to others. The most common:
- Kotlin for most of the backend code, but Java for shared libs. We still use Java 8 for some libs which may be used in Android, that's an unfortunate reality - Gradle for build config - Spring for application architecture And few things that may significantly improve your dev process, but are not so common: - Spring Reactor (and Webflux) for processing data and requests. Takes a time to learn, but it worth it - Thymeleaf for UI - Spock for testing. Highly recommended for designing tests - Testcontainers for integration tests - Micrometer to see what's going on with your app. I.e., to export all internal metrics to use with Prometheus/Grafana/etc For the environment - SDKMan to manager the environment - Gradle Application plugin or Google's Jib to pacakge your app. First prepares a Zip with all binaries, second a Docker container - IntelliJ IDEA - Github Actions - turns out to be the most usable CI. Though the Jetbrains TeamCity may be better for a large team > Kotlin for most of the backend code, but Java for shared libs. We still use Java 8 for some libs which may be used in Android, that's an unfortunate reality Considering Kotlin is a supported, first-class language on Android, why not write your shared libs in Kotlin as well? I'm talking about open-source libs, i.e., I don't know who is going to use the lib, which env and target language they have, etc. So I think that Java is the best middle ground here because it guaranties the full support of JVM features and 3rd party tools. I mean just avoiding a risk that it would be incompatible with something. - Language: Java 17/Kotlin - API Layer: Quarkus (most projects https://github.com/quarkusio/quarkus), Vert.x (small projects https://vertx.io/) - DB: Postgres, in-memory H2 for simple stuff - Testing: JUnit 5, Testcontainers to automatically start + stop DB Docker containers with tests (https://www.testcontainers.org) - Mocking: Mockito (https://github.com/mockito/mockito) or Mockk (Kotlin, https://mockk.io) - Dependency Injection: CDI (built into Quarkus, for Vert.x you can initalize Weld when the app starts https://weld.cdi-spec.org) - Build tool: Gradle with Kotlin DSL - Other tools: I have been thinking of writing up a series of articles on this. Without going into too much detail: * IDEA * Deploy on Google App Engine, Digital Ocean App Platform, Heroku, Elastic Beanstalk, etc - get out of the ops business entirely. * Guice as the backbone, no Spring/Boot. I wrote a tiny dropwizard-like "framework" to make this easier: https://github.com/gwizard/gwizard but there's a laughable amount of code here, you could build it all from scratch with minimal effort. This is about as lightweight as "frameworks" get because Guice does the heavy lifting. * JAX-RS (Resteasy) for the web API. IMO this is the best part of Java web development. HTTP endpoints are simple synchronous Java methods (with a few annotations) and you can test them like simple Java methods. * Lombok. Use @Value heavily. Cuts most of the boilerplate out of Java. * Junit5 + AssertJ. (Or Google Truth, which is almost identical to AssertJ). * Use functional patterns. Try to make all variables and fields final. Use collection streams heavily. Consider vavr.io (I'll admit I haven't used it in anger yet, but I would in a new codebase). * StreamEx. Adds a ton of useful stream behavior; I don't even use basic streams anymore. * Guava. There's just a lot of useful stuff here. * For the database, it really depends on what you're building. Most generic business apps, postgres/hibernate/guice-persist/flyway. Yeah, folks complain about hibernate a lot but it's a decent way to map to objects. Use SQL/native queries, don't bother with JPQL, criteria queries, etc. * Hattery for making http requests (https://github.com/stickfigure/hattery). This is another one of mine. I make zillions of http requests, functional/immutable ergonomics really matter to me. * Github actions for CI. * Maven for the build. Yes, it's terrible, except for every other build system is worse. Gradle seems like it should be better but isn't. I'd really love some innovation here. Sigh. Cool, it is a lot to start researching but you sound like you use a very similar style to things I am used to in other languages. On guice/gwizard/maven, if I understand correctly I would be defining new guice DI for something like a message broker (and gwizard's solutions for similar modules might serve as a template) while probably just using direct dependencies in maven for something that doesn't need to be mocked in unit tests or replaceable in production? You could make a new guice module for the message broker, but you don't have to. If you want to use a message broker, just bind the service object as an eager singleton in your application module. The main reason to make a separate guice module for the message broker is if setup requires a lot of boilerplate. You can put it all in a common jar artifact and include that in different services. But that's overkill if you just have one service, or if the broker has a fairly friendly interface to start with. Guice is just a little bit of structure to bind together Normal Java Code. You don't need to wrap services or do things eg "the spring way". Just use the service; if you find yourself repeating code, consider abstracting it into a separate module. Gradle (with Kotlin syntax), Spring Boot (vertx, ktor or for small or microservices), Kotlin, IntelliJ. That would be a "modern" stack for me. If you can't use Kotlin, Java has improved a lot since 1.6 you will be pleasantly surprised. I recommend you start an intellij (Free edition if you want to, even if I still recommend the paid one) and follow the springboot kotlin tutorial below. That will give you a good idea of what the ecosystem looks like these days. Oh and make sure you start with JDK17. I still see people starting projects with 8, you don't want that! I've been doing Java non-stop since before 1.6. I just started a new project, and it's * IntelliJ * Standard enterprise Java JEE 9.1 (JSP, JPA, EJB) * Payara app server * Twitter Bootstrap * Maven * Test driven development using TestNG + AssertJ * Postgres + Liquibase for schema management Code samples now come from https://www.baeldung.com/ Just curious - you mention JSP. Was that mentioning that yeah, JSP happens to be part of JEE or are you actively using it? I haven’t heard of a new project using JSP for a while. Yes, my new project uses actual JSPs. Granted, there aren't tons of pages to be built in this project, and certainly nowhere near the scale that might call for a different option. For even a few dozen pages, JSP is still just fine. IntelliJ idea is the best IDE. JDK8 incorporated a lot of great functional programming ideas (though the streams library is awful.). Up through JDK17 there are many improvements including a more scalable runtime. I haven’t been paid to work with Spring since 2013, every project I’ve worked on since has used Guice, maybe Dropwizard. JAX-RS is the dominant paradigm for web back ends these days, particularly if you are writing single page applications. I think the Streams designers did an amazing job. One of my favorite things about modern Java. Yes, it's more verbose than Python list comprehensions, but it's both higher-performance (parallelism that just works) and more productive (static typing means it almost always works as intended the first time). That's just not true about the parallelism. The work stealing mechanism used by streams doesn't really work. Frequently I've seen people get something like a 1.7x speedup on an 8 core machine and was able to get a 7.8x speedup on the same machine using a ThreadPoolExecutor. For common "embarrassingly parallel" problems there are two parameters you need to set: (1) How many threads to use, and (2) How fine to subdivide the problem. Often the basic work unit takes much less time to complete than the time it takes to switch between threads. For instance a raytracer can probably trace one ray in less than the time it takes to communicate between threads. If you try to parallelize a task with too fine a granularity you get a slowdown not a speedup. You might find you get a good speedup over a fairly wide range of granularities (you might do well with anywhere between 100 and 10,000 rays) but batching of some kind is essential. As for the thread count it depends on if the job is CPU bound. A CPU bound job needs about as many threads as you have cores or SMT "threads". If the job is I/O bound you usually need many more threads to maximize performance, but it's tricky. A web crawler might be able to support 100's or 1000's of threads but if you point all those threads at one server you might crash it, get banned, or both. If the awkward streams API bought you good performance and reliability (let's see... just about zero support for error handling) that would be one thing but it doesn't. Static typing working so well is not a special feature of the streams API but rather one of the rather brilliant engineering that went into JDK 8. You can easily write your own "map()" functions and other higher-order functions that do many of the things the Stream API does. It would really be nice to see a better third-party API. >I haven’t been paid to work with Spring since 2013, every project I’ve worked on since has used Guice, maybe Dropwizard. This is the opposite of my experience.
I worked with Java a lot for the last 10 years or so. In the last 3 years literally each request I got for implementing stuff in Java also required Spring (Spring Boot) - and that was dozens of clients. Spring Boot (embedded Tomcat/Jetty/Netty) Lombok Gradle, Guava JUnit 5, testcontainers, WireMock Logback, Slf4j Okhttp, Open Feign, RestTemplate Micrometer OpenApi, swagger Liquidbase, jooq - db stuff This is your run of the mill stack Dropwizard, Vert.X seem to be less used nowadays, Spring has mostly won the show Heard people using Kotlin, Quarkus, Micronaut but that's niche stuff IMO: IntelliJ for IDE (Community edition is free). #1 reason is it supports Kotlin and Groovy very well out of the box. Eclipse is still a plugin disaster, and the language support aside from Java is pretty bad, although I haven't bothered to check in a few years since IntelliJ CE was released. Gradle for builds. It is still copy and paste setup, but at least you can do a lot more things than rigid Maven. Groovy + CompileStatic (personally) for the actual JVM language but admittedly I haven't tried Kotlin yet. Even with closures and other improvements, base Java can't compete with either of those. Spring Boot for your enterprisey stuff/REST services which you are likely using it for. It's such a standard at this point. Unit tests: Spock. Spock is awesome. And very well supported by IntelliJ for autoformat, another BIG reason to use IntelliJ. Man, web frameworks on Java that don't just use it for an AJAX service layer? Who knows. Eclipse as IDE (actually STS - Spring Tools Suite edition) for both Spring Boot and JBoss Tools (yes there's enough work for JEE - WildFly or JBoss EAP). The build would be most of the time Maven (including the assembly plugin) and sometimes would create native Quarkus images for cloud tools (read serverless). I can't speak to how prevalent it is in the industry, but something my team has started doing in our web services is building with GraalVM and deploying native images. The build time can be super long, but the benefit is incredibly fast start-up time, which really benefits horizontal scaling. We're using Quarkus (https://quarkus.io), which is largely built on Vertx which was mentioned elsewhere, but other frameworks (Micronaut (https://micronaut.io) comes to mind) make it easy and SpringBoot is also working on support. If your doing containers/kubernetes native images feel like the way to go. Spring Boot is the go-to solution for Java where I work. And definitely Intellij as IDE. And Maven. Don't forget Maven. This is my experience. For context I do a lot of contract work mostly in banking, ecommerce and insurance. what about lombok?
Edit: just curious if you think it's standard Lombok seems to have a 50/50 split of people who love / hate it. I am firmly in the No Lombok camp! My reasons are; * IntelliJ is very good at generating boilerplate getters / setters etc * I found sometimes the annotation processor would get out of sync with the IDE resulting in compilation issues until the processor was run again * Java 17 records replace a lot of the functionality As far as I can tell the lombok is certainly less used than say 5 years ago. Java records can help somewhat but as others point out, theay are not compatible with JPA, sometimes you get real value from Lomboks @Builder etc. On the other hand if you combine lombok and JPA entities you can easily shoot yourself in the foot (autogenerated hashcode and equals can cause issues in some cases) With records now being supported in Java, wouldn't Lombok be less needed? Unfortunately not. Records are not compatible with JPA, so classic beans with getters and setters would still be a choice for many people. Record-friendly ORMs do not exist yet (I’m currently working on one). Could you please share your ORM? I would really like to use java with much less reflection. If you can send me an email at oss+hn[at]esoftworks.com, I will let you know when I will have beta quality code on GitHub. This is a personal side project exploring annotation processing and targeting modern Java (17+), some results will be ready probably in 2-3 weeks. Feel free to star this repo and comment: https://github.com/ivan-gammel/orm16 I concur Kotlin + Dropwizard. Avoid Hibernate, go with JDBI. If I was starting a new project I'd look at Jooby, which looks pleasant and does very well on TechEmpower benchmarks. JDBI is pretty slick. We used it as a previous company. Previous experience was with Hibernate, lower level JDBC, and some other half baked proprietary ORMs. Good summary of the language-level changes here: https://piotrminkowski.com/2021/02/01/new-developer-friendly... ETA: actually if you haven't used it since 1.6 you'd want to find an article on Java 8 as well that covers Streams. I'm about 3 years out of date on Java, but if I were spinning up a new project it would be: * Latest JDK * Spring Boot * JQuery/Bootstrap * Eclipse (with Vim keybindings plugin) Caveats: * If it was a personal project or only a very small team, I'd start with Kotlin * I haven't tried IntelliJ in quite a while and would give it a shot to see if I wanted to switch off Eclipse now Make sure you do give it a try and beyond the initial discomfort too. It has improved leaps & bounds. I’ve seen the Micronaut framework used instead of Spring Boot a lot recently for AWS Lambda Spring Boot wrapped in a Docker container and a frontend written in JS using React, Angular or similar. So maybe the frontend and deployment has changed. The rest probably not so much. Java versions 8 and 11 are by far the most common. Lambdas were introduced in version 8. If you ignore the way frontend is made (JS + rest api ws. server-side rendered html) and how stuff is deployed (containers vs. war-files); amazingly little has changed in Java the past 10-15 years. We have a multi-project gradle build, all our code is in Kotlin, we use micronaut as our base framework and we use IntelliJ as our IDE - this setup has worked great for us over the past year. Many use other languages on the JVM. Scala, Clojure, Kotlin etc. Besides the naked functionality, the language communities and cultures have their varying strengths. Eg quality of answers or libraries you easily find. The years long constant stream of deserialization vulnerabilities, like yesterday's Spring RCE, are also largely absent from other JVM languages. Bazel, ErrorProne, Dagger, AutoValue, IntelliJ IDE: IntelliJ IDEA https://www.jetbrains.com/idea/ Nothing else seems to come close, they have a Community version, nowadays Eclipse and NetBeans both feel slow but Visual Studio Code with Java plugins lacks refactoring abilities one might expect in an IDE for non-trivial projects. Also, if you get the Ultimate package of their tools, you get all sorts of other useful tools, personally i also enjoy WebStorm and DataGrip for developing front end stuff and working with databases in a separate tool. JDK: whatever the LTS release of JDK is at the time, based on the kind of work that i do (so JDK 17 now) https://adoptium.net/ As long as you're not stuck with JDK 8, you should be fine in regards to this. But you can definitely enjoy some speed improvements across the releases as well as new language features as well as things like helpful NullPointerException messages. Personally, i'd sometimes also look towards OpenJ9 as an alternate runtime (due to lower memory usage), but that project's future isn't very clear (at least in regards to available container images) last i checked. As for frameworks, pick one of the following: Here's a rough performance comparison if you care about that sort of stuff: https://www.techempower.com/benchmarks/#section=data-r20&hw=... Build tools: personally, i just use whatever Docker images to base the apps on when available and something like Ansible when not. For the actual toolchain, Maven is still pretty dependable, i guess Gradle is also okay. You might occasionally run into tools like Bazel or Jib, experiences there might vary. App servers: if you need an application server for some reason (e.g. deploy app as .war), Tomcat is still a good option. If you need the EE functionality (e.g. Java EE which is now Jakarta Java), you might need to reach for something like TomEE or Payara Server, though i haven't needed to do that for a few years at this point, since Spring Boot embeds Tomcat and that is good enough for almost all projects. > Nothing else seems to come close, they have a Community version, nowadays Eclipse and NetBeans both feel slow After not using Eclipse for 10 years, I had to use it again last month for a very large existing project. I was pleasantly surprised. It felt faster than IntelliJ. Huh, that is pretty nice to hear! I'll probably need to download it sometime and try it out again. I last did 1-2 years ago and it still wasn't quite passable in a Java project with 4000-5000 source files, though maybe that's because of the plugins involved (e.g. myBatis for ORM which has Java interfaces and XML mappers for SQL queries) or mixing technologies like JSP/JSF and also having JS files with front end resources in the same codebase. Of course, i'm talking about the full Eclipse with the JDT package and a bunch of other stuff, some folks have more slim installs: https://www.eclipse.org/jdt/ In that regard you can indeed have a lot of flexibility. Oh and i think that a while ago they also tried having lightweight solutions like Che and Theia as well. Recently i've actually started splitting up the old legacy projects into multiple monorepos (e.g. "back-end" and "front-end" folders with the occasional supporting service in there as well, not necessarily everything in a single repo) and the impact has been pretty noticeable! For starters, separate instances of IntelliJ and WebStorm for different kinds of code (Java and JavaScript/TypeScript) seem to work far more quickly, the builds also are generated faster (since fewer resources to copy) and i don't need to cry when i forget to tell the IDE to ignore node_modules. The Eclipse incremental compiler is faster than IntelliJ on any decently sized project. Something like 20-60 times faster for us (<1s vs. 20-60s). I think the UI of IntelliJ is snappier, so for small projects that leads to people saying it's "fast". What’s the JDK version people use today? My company’s stack is still on java 8. Most of our old services are still on 8, slowly migrating those to 11. Sometimes it's trivial, other times it's a pain. Anything new is at least on 11 and 17 where possible. - IntelliJ - Java 17 - SpringBoot 2.6.x - Hibernate - Maven - MySQL or Postgres - Liquibase - Swagger/OpenAPI - Docker Which JDK distribution is used today? There are so many to choose from. IntelliJ Idea for sure. Also using IntellJ. But how is the landscape with the other IDE's these days - is NetBeans keeping up? Netbeans died an unfortunate death once it moved to the Apache foundation and Sun/Oracle funding died out. https://trends.google.com/trends/explore?date=today%205-y&q=... Unfortunate, because it had (has?) a great Swing and UML editor, built-in for free. Maybe I'm wrong and it's awesome now, but I haven't used it for a while in favor of Eclipse, and now, IntelliJ. This graph illustrates the IDE popularity between Intellij and Netbeans. IntelliJ became preferred over Netbeans about mid 2014. https://trends.google.com/trends/explore?date=all&geo=US&q=i... Netbeans was really great, maybe still is, but the noise jetbrains made with the astroturfing advertizing has jetbrains dominating everything. IMHO Netbeans was ahead of idea in many ways. But since they didn't buy commenteers to hype their product it's pretty much nowhere, at least I don't know anyone who uses it. I'm someone who has regularly recommends Jetbrains software (including IntelliJ and Resharper) to others in comments, and now I'm wondering if they forgot to send me my check. I think I'm regarded as something of an intellij zealot at work but now a bunch of people have switched. Hopefully I'll receive my check soon. I too lack a check. I know developers who still use it, but they refuse to give IntelliJ a chance. I am using it now because the team is using it, but cant figure out in which way it is supposed to be better then Eclipse. It looks somehow better, but it seems strictly inferior in terms of what it does for me. I find both mysteriously stop working on a project for a while so I keep them both.
Eclipse has far better refactoring. IntelliJ refactors text files that are not Java and can easily break stuff when eclipse refactors are always safe. IntelliJ updates text strings but it's not always correct in doing so, é. G. A comment that says "_don't_ use a.b.C" might get refactored.
In eclipse you can often safley "code backwards" i.e. break an API and then fix all the red dots, usually with auto fix options. IntelliJ misses a lot of necessary fixes until you compile. That can add hours of work to a big change. I'm very curious to hear what Eclipse does that IntelliJ does not match. Incremental and partial Java compilation. Partial compilation is the notion that partially compiled software is still usable and something you can debug or introspect on. The IDE compiles while you type, it will detect syntax problems and as soon as you fix them they go away. Error markers in intellij are nowhere near as fast and you can't trust their presence or absence to be correct either. Intellij does that a little bit of incremental compilation. They half integrated the eclipse Java compiler at some point but they never really made using it a thing. Most projects just hand off compilatio to Gradle or maven, which means you lose a lot of time waiting for that and dealing with various caches in intellij and gradle/maven getting out of sync with each other. The process for fixing that generally involves boiling the oceans and running the CPU at 400% for a few minutes. Eclipse compiles two orders of magnitudes faster when you have it properly setup. I'm not exaggerating. It's really good at this. Intellij users have never seen this level of performance. I've tried to explain it a few times to users that insisted they had intellij configured just right. The minimum execution for a unit test after a 1 character code change is the key benchmark for this. Run a test, change something trivial, run it again. If that takes more than half a second and has a noticeable delay, it's not fast. Eclipse user to be closer to 50-100ms. Even on a (now) ten year old laptop. With intellij, it's closer to 3-5 seconds. They have improved things over the years but it never got even close to that level of performance. Thanks, that sounds very cool. As you say, intellij basically hands this off to gradle or maven. Does Eclipse interpret those natively or do you have to reproduce your maven build in the Eclipse gui? Compilation of everything, how it shows compile errors and warnings. I see them in tree, in list, easily and quickly all of them. All of them for whole project at once and trustworthy. Less bogus warnings and contraproductive suggestions. I never needed to fiddle with "command line shortener" ridiculousness in Eclipse. Better code navigation and discovery. Eclipse always finds everything, every called and callee to depth. Same with inheritance. Even where Idea has same views, for some reason they hide it and only former Eclipse users stumble on it. Actually safe refactorings. Idea occasionally "refactors" by creating bugs. I had some cases where Idea simply formats code wrong. And it was impossible to configure to formát it right. Also, Eclipse compile by default. It is ridiculous to have to remember to press shortcut to compile in modern IDE. I know it is configurable, but still ridiculous default. Square selection. Elipse keeps a complete Java representation of the source code in memory, (not the classes) that's why it can find compile errors before saving.
This comes at the cost of lost of RAM, some projects are just too big for eclipse so IntelliJ is your only option.
But that eclipse model can be used for lots of cool tricks, you have access to it in the plugin API, so for example you can enforce coding standards before even saving code. I would argue that if a project can't fit into Eclipse with 32 GB RAM then perhaps the code base has become too large to manage and ought to be split into separate projects with dependencies. In eclipse java code is generally already split into projects, in a workspace, you can close projects to save ram. When you can get it all in memory, you get the benefits of eclipse refactoring, when you can't you don't. Ability to write code that is safe to refactor is one of the great things about Java, so it's a shame if you can't benefit from that. And what are the functions that you use that work better in Eclipse? Eclipse immediately tells you what is broken when you change an api. IntelliJ does not. You can't stop IntelliJ from saving work. I like to kick of a build, and work on some new stuff while it's going on without saving until the build completes. That workflow is impossible in IntelliJ.
You have to down tools, for a long build with lots of tests that can make IntelliJ slower over all. IntelliJ generally more responsive for most work, but that's because it's not using Java's type system to find errors as you work, errors are deferred, which often means they take longer over all to fix. It just takes two check boxes to uncheck to disable that in IntelliJ. I agree it is disturbing that it is a default at first. But it is at least configurable. Which version? It wasn't possible last time I checked and Jetbrains had close-no-fix on various related bug reports. Last EAP version but it was there at least since last year. Eclipse shows me all errors in whole project at once. This is biggest one. The hierarchy and callers hierarchy always work, I can rely on them way more then in Idea where they sometimes miss things. Much much better full text search. I can search through multiple projects. Not just root. Square selection. It costs money, so it is a value statement about you as a developer. Either you are "worth it for your employer", or you are "worth it for yourself". (I personally still use Eclipse) After doing some "modern" spring boot / hibernate, I came away wondering how anybody ever thought that was a good idea. The switch to kotlin with ktor took less than a day, and my sanity has been preserved. Over the last five years, the Java Platform has seen a tremendous amount of evolution and improvement in a variety of areas, including: language features in Java, Kotlin, and Scala; Functional Programming; dev environments; test workflows; Reactive; Stream processing; and distributed data. Is Scala still in trend? It's Kotlin now. Kotlin has similar expressibility and extensibility, without Scala pitfalls. (Scala pitfalls that people didn't like included new versions having breaking changes, complexity, theoretical/academic features that weren't necessarily useful to consumer applications, and slow build times). New versions don’t have breaking changes, they are just not binary compatible between major version upgrades which is true of many other languages as well.
Regarding complexity - scala has many features due to having a small number of clever primitives. Kotlin special cases many common cases, but imo that will be a more complex language down the line. I really don’t know what do you mean by academic features — one can make haskell libs with scala but they are libs, not language features. And build time-wise it is not that much slower than kotlin. I would say it is no longer a hyped language (Kotlin took over that position), but it recently became Scala 3 which was a huge revamp. It polished some of the edges regarding implicits (which is a really useful and novel feature), and it has a very advanced and elegant type system with optional null-checking. Not really. It hasn't seen growth for a while. It's big in the data science world because of Spark. For general purpose JVM apps I see people mostly going with Java or Kotlin. Personally, after the log4j fiasco, I wouldn't touch Java. The standard ecosystem setup is to use all the major 3p libraries for all your functionality (Jaxrs, swagger, log4j, jersey, e.t.c) While this generally works, the ecosystem is full of holes (like log4j), and crappy behavior. You get things like "javax.ws.rs.ProcessingException: Already connected", exceptions which mask underlying issues like not being able to find the endpoint, or SSL certificate error, mainstream clients for things like Redis having issues with multiple connections and unable to switch to master nodes, and so on. The core language itself is very "dirty" (Integer vs int, requiring a class for the main function, e.t.c). The standard way annotation processors add functionality is to basically write out java files, (or in the case of the ever so popular Lombok, they hack the AST). Because of how annotation processors are run, often times an error during annotation processing with dependency injection will result in very cryptic errors, often about things that were working before that you didnt change. And on top of everything, jdb debugger is pure garbage, forcing you to use bloated software like IntelliJ for any decent functionality. Yes, you can learn the ecosystem and its idiosyncrasies, or you could just write the thing in Python or Node with a much more efficient workflow. Network latencies dominate the processing speed these days, and infrastructure is cheap compared to developer time. Pythons indentation errors and complete lack of variable types make it a kids scripting language at best. It is only useful for quickly cleaning data up for clock watchers at Mega Corp XYZ and its libraries like scikit learn which are kinda cool but it's best to link some python scripts and do everything else as a Java project. Data science cleaners / janitors are usually very limited energy wise from fapping and have that cuck squarish personality thing going on so they like pythons lazy approach to coding. > Network latencies dominate the processing speed these days I want to see data on this. It gets repeated over and over but this doesn't match my experience at all. Am I crazy? It takes me about 250ms to load hackernews as seen on the browser debug network tab. The total compute for that request is minimal. Speeding this up may reduce total infrastructure costs, where if everything is kept static you will see benefits long term, but in terms of reducing total latency, it will be next to irrelevant. I can list a ton of tools I use daily that are incredibly slow, but don't even need the network most of the time. By "incredibly slow" I mean comparing what it does versus how fast it could be on an average machine. Network and other I/O latency is often used as an excuse and sweeping generalization. It's never that easy. You need to actually look at a running process and gather data about it before you can make claims about what the bottlenecks are. Also even if there are constant factors that you cannot optimize it doesn't absolve a program from being slow in every other aspect, secondly there are techniques to mitigate and isolate latency bottlenecks.
And this is how you could create your koin context: class SomeClass {
val foo by koinContext.inject<Foo>()
}
Modules can be tied to life cycles on Android and there are a few more features like being clever about co-routine scopes. But there's not a lot more to it in terms to using it. Very simple code to write. Low overhead. It's all just function calls. class Bar()
class Foo(bar: Bar)
val myModule = module {
single { Bar() }
// get() knows the type from the argument position at compile time
// and it looks the object from the context by type
single { Foo(get()) }
}
// trigger this in your main or at application startup
startKoin {
modules(myModule)
}
// if you want to use inject, you can use a global variable for getting at the context
val koinContext by lazy { GlobalContext.get() }
Kover: automatic code-coverage reports from JaCoCo/IntelliJ (https://github.com/Kotlin/kotlinx-kover)
Ktlint + Detekt: Kotlin linting/static analysis (https://ktlint.github.io, https://detekt.github.io/detekt)
PMD, Spotbugs, Nullaway: Java linting/static analysis (https://pmd.github.io, https://spotbugs.github.io, https://github.com/uber/NullAway)
- Spring Boot
- IntelliJ
- Gradle or Maven
- Java 8 features (for various reasons most of my clients do not use version > 8)
In practice, you're most likely to see Spring Boot in existing projects since it's so boring and dependable, though perhaps sometimes you'll also run into the legacy Spring framework (which can be a pain to deal with) or even some of the other ones. - Spring Boot: mainstay of the Java ecosystem, has a really large amount of integrations and the Boot version also simplifies getting up and running, about as safe of a bet as Rails for Ruby or Django for Python
- Dropwizard: probably the closest competitor to Spring Boot in my eyes, but is a more loose collection of a variety of pretty much "standard" libraries, has decent developer experience
- Eclipse Vert.X: pick this if you want to work with reactive programming, last i checked it didn't feel quite feature complete, but the performance numbers speak for themselves, even if it feels a bit niche
- Quarkus: another modern option that's tailored for the development of performant web services, got a lot of hype in conferences in the past few years
- Helidon: pretty similar to Quarkus as far as i'm aware (at least as far as the positioning in the market goes) so figured i'd also mention it