Request Issue

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Website Section

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Proposal Details

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Author References

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The purpose of this repository is to provide Java-related content for everyone and allow that knowledge to be used.

However, I don't see a LICENSE file in this repository.
How is the existing content of this repository licensed?
And what about third-party/Community contributions? How do they know which license they provide their content under?
Does contributing require signing the OCA? If so, which one (or which projects) is required for this repository?

I think it might be important to sort this out before the first actual (content) contributions.

The README.md file refers to the root web page of inside.java in a manner suggesting that the target contains an announcement on accepting contributions to dev.java:

I wasted at least 15 minutes trying to find the respective announcement on the target website but was unable to find it. I'd say that this link is effectively broken. The inside.java web page contains many news items, and if the respective announcement is contained in one of these many, the link in README.md should refer to that news item instead of the root page.

I think dev.java should contain an article on regexes.

Specifically, I would suggest that such an article includes:

• What are regexes?
• How can regexes be used in Java?
  • using String methods (matches/replaceAll/split)
  • Compiling Patterns
  • using Matcher for finding occurences in Strings, working with groups, etc.
• quick overview on regex features

The Storing Elements in a Container with the Collection Interface part of the Getting to Know the Collection Hierarchy article contains the following sentence:

Since a Collection is a set of elements, there also set operations defined on the Collection interface:

I think this should use Set instead of Collection.

The said article is not a part of this repository.

This request may be a bit controversial since it is not that specific to Java but I see many people learning Java experiencing issues without knowing what a debugger is and how to solve it.

We often refer to this Stack Overflow post when this question is asked in our JUG (which has a focus on helping new Java developers).

I propose to add an article that explains

• What is a debugger?
• How can debuggers be used?
• What is a breakpoint?
• What common functionality do debuggers in IDEs provide
  • ideally IDE-agnostic but including things like Step Into/Step Over/Resume
• How does a debugger help me solve problems? Why are they so useful/important?
• Links to debugging documentation of (common) Java IDEs
  • https://www.eclipse.org/community/eclipse_newsletter/2017/june/article1.php
  • https://www.jetbrains.com/help/idea/debugging-your-first-java-application.html
  • probably also something for VSC and NetBeans?

Non-Goals:

• How do (Java) debuggers work internally?
  • This could be the scope of another article but I am talking about an introductory thing.

There are currently 4 articles about exceptions on dev.java.

However, none of them seem to explain what exactly a stack trace is, how to read it and how to find out where the issue is.

I frequently see new Java users (e.g. students) being confused by (especially bigger) stack traces with no idea on how to debug them.

While this Stack Overflow post explains it quite well, I think this is a good fit and would be a helpful article (especially for referencing it to new Java developers).

I would like such an article to contain the following:

• What is a stack trace?
• When is a stack trace displayed on the console (or in other logs)?
• What is a Caused By section?
• What is a Suppressed section?
• What should people look at/focus on when reading (bigger) stack traces?
  • Differentiating between own code and other code (in frameworks)
• Why is it often a bad idea to use System.out.println("error"); instead of e.printStackTrace(); (or re-throwing) in a catch-block for exceptions that shouldn't happen?

I would like to ask about adding some endpoint that emits a list of articles on dev.java, e.g. a sitemap (though it would be useful to have access to the article titles).
This would allow for building tools for finding and referring to articles without needing to scrape the site.

In https://dev.java/learn/java-io/file-system/listing/, it says:

Remember: The returned DirectoryStream is a stream. If you are not using a try-with-resources statement, do not forget to close the stream in the finally block. The try-with-resources statement takes care of this for you. You can learn more about stream in the Stream section.

What does "...is a stream" mean? A java.util.stream.Stream? A java.io.InputStream or java.io.OutputStream? It is neither. Maybe the author meant "...is an AutoCloseable"?

Since Sequenced Collections were introduced in Java 21, an article explaining them could be added to the section The Collections Framework.

Alternatively, information about sequenced collections could be added to Getting to Know the Collection Hierarchy and Using Maps to Store Key Value Pairs.

While there is an Introduction to Java Reflection, I don't see any article about the APIs defined in java.base/java.lang.invoke. I think it would be nice to have something explaining these APIs (MethodHandle, VarHandle, potentially interactions with invokedynamic) as well.

@venkats contributes the Refactoring from the Imperative to the Functional Style series to dev.java.

In the series introduction/index page, there is a table containing all tutorials as well as how these are transformed.
The Imperative Style column of that table contains cells like foreach(...) { if... } even though Java uses the syntax for(TypeName variableName : someIterable).

I suggest changing this in order to not make it look like Java has a foreach keyword.

The FAQs on dev.java contain a link Common Problems (and their solutions) which links to https://dev.java/learn/getting-started/#anchor_9.
However, #anchor_9 is not available on that page. It should instead link to #common-problems.

The link is specified here

Explain the RandomGenerator API introduced by JEP 356. Inspiration: https://nipafx.dev/java-random-generator/

The article Creating Arrays in Your Programs explains how arrays work but it doesn't mention arrays of arrays.
I think it should cover how to create arrays of arrays, how to access them and the possibility of creating arrays of arrays where not all inner arrays have the same size (not rectangular).

There is a typo error in Home > Tutorials > Java Language Basics > Using Operators in Your Programs

Under Bitwise and Bit Shift Operators Section it is written Bitwise | as Bitwise &

Request Issue

No response

Website Section

No response

Proposal Details

Article on Java certification. Chad ok'd idea over email

Author References

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Request Issue

#8

Website Section

Home --> Tutorials --> HTTP Client

Proposal Details

• Why this API and not other HTTP clients?
  • Lightweight
  • No dependencies
• Fetching recipe data from TheMealDB
  • Building an HttpClient
  • Building an HttpRequest
  • Getting an HttpResponse
    • Method 1: synchronous
    • Method 2: asynchronous

Author References

• https://joshaustin.tech/blog/how-to-concatenate-strings-in-java-like-a-pro/
• https://joshaustin.tech/blog/getting-started-with-rife2/
• https://joshaustin.tech/blog/those-sneaky-nullpointerexceptions/

Sample request issue body.

Approved Content Discussed in #24

The README mentions:

All content must start with a Content Proposal. This will be in the form of a GitHub issue using the Content Proposal issue template.

and it differentiates from requests as it seems to expect a [requested] issue before that:

Look through the requested issues and find something that you feel uniquely capable of writing

This also seems to be strengthened by the Content Proposal issue template which expects a Request Issue.

However, it seems that the [approved] label is typically put on accepted content requests (at least after this repo was opened for Community Contributions).
Furthermore, both #45 and #49 didn't seem to need a proposal issue, the request (followed by the future author being assigned to it) seemed to be sufficient.

Therefore, I propose to remove the distinction between content proposals. I would suggest to:

• Add an issue template for requests (or remove the Request Issue field from the Content Proposal template).
• Create a Pull Request template from the current Content Proposal template since it makes sense for PRs to mention the request issue (and all other fields from there).
• Clean up the tags so only the tags actually being used are listed. For example, I haven't seen any usage of the [in progress] label.
• Adapt the README to reflect this workflow.

Request Issue

No response

Website Section

Learn --> Tutorials --> Your First Java App.

Proposal Details

Would be great to have a getting started with Java article and IntelliJ.

Author References

Marit van Dijk (@mlvandijk) would be great to complete this ask 😸

Get somebody from zero to "Hello, World":

• brief explanation of what a JDK is and where to get it (at least partially, this already exist on the site ~> link there)
• explanation of editing a .java file with a text editor and how to run it with java (now javac - see JEP 330)
• shortest possible HelloWorld (ignoring JEP 445 for now)
• brief explanation of the involved concepts with links to the articles that explain them in more detail

Request Issue

No response

Website Section

Learn > Tutorials

Proposal Details

I would like a session with fixation exercises to be added to the dev.java so that we can put into practice what we have learned. It may not necessarily be a program for us to do. Sometimes it could be a quiz, I don't know. It would be very interesting <3

Author References

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The collections framework is covered in great detail and that includes mentions of concurrent data structures but that section does not strategically explore how to use them in a concurrent program.

The Classes and Objects section mentions covering enumerations. However, that part is missing.

I think a page about enumerations should be added there:

• What are enumerations?
• How to create them?
• What functionality do enumerations provide in Java?

A common source of confusion among (somewhat) new Java developers (especially when they are packaging their first application as a JAR) is resources on the classpath and how they are different from files.

I would request an article clarifying these things, specifically the following:

• What's the difference between resources and files?
• When I access a file in my source folder using java.io.File (or similar), why does it not work in a JAR deployed somewhere (in a different directory, on a different computer, ...)
  • Why should I not use files for accessing anything in the source folder?
• What does Class#getResource/Class#getResourceAsStream do?
• What's the difference between getClass.getResource("a.txt"), getClass().getResource("/a.txt") and getClass().getClassLoader().getResource("a.txt")?
  • Why does it not find my resource when I use the wrong one?
• Where should I put resources?
  • with Maven/Gradle but also in plain Eclipse/IntelliJ/VSC projects

For new Java developers, the Staying Aware of New Features section isn't that useful (in my opinion).

Hence, I propose moving it down somewhere after the Mastering the API section because Getting to Know the Language and Mastering the API are the sections that seem to be most useful for new developers.

Furthermore, it might be a good idea to sort other in order of difficulty so the most basic articles are first and each article appears after the articles it depends on.
For example, the Refactoring from the Imperative to the Functional Style series seems to be more advanced compared to other topics in that section so it may be worth moving it a bit down.

dev.java provides a section Fundamentals of Security using JDK Libraries.

Since the Key Encapsulation Mechanism API has been added in Java 21, it could be useful to add an article for that.

Approved from Content Discussed in #24

Hello! I would like to submit a correction to the Using Lambdas Expressions in Your Application page, and thought of submitting this fix in the form of a pull request, but I'm unable to find the sources for that page. The Contributing to Dev.java page only lists this GitHub repository, but it does not appear to contain the respective source code.

Where is the correct place to file such a pull request, or at minimum to report the issue?

In the section Getting to Know the Language on https://dev.java/learn/, the description of the Exceptions article series is as follows:

Using exceptions to handle errors and other exceptionnal events.

I think it should be exceptional instead of exceptionnal.
In the description on the series page, this is stated correctly.

This issue does not request nor propose a new content. But it stands for reporting a mistake in the website dev.java

In the page Getting Started with the JDK Flight Recorder, at the section "Enabling JFR on Startup", it is written :

To enable JFR on startup, include the VM argument -XX:StartFlightRecorder

As far as I know, the right option name is -XX:StartFlightRecording. The mistake happens thrice on the web page. The other pages are OK.

Please, can you fix it ?

Hello everybody! I hope you are well.

I would like to give an idea to everyone who maintains Dev.java.
I'm learning a lot there ❤️ I've already completed several topics and this makes me very excited and motivated to always want more. But I've been noticing something for a while: I noticed that there are no tutorials on networks (http) and on Databases (Maybe it's me who's not finding it, even though I've already viewed everything and haven't found it).

Could you add tutorials related to this? It would also be interesting, in addition to the already added JavaFX tutorial, Also have a tutorial related to swing? It would be interesting, since swing is easier to learn than JavaFX. Swing would be like a prelude to JavaFX.

It would also be helpful if the tutorial related to threads and concurrency were added to Dev.java.

I know that all this already exists in the documentation tutorial, but it would be nice if it were more exemplified in the dev.java website.

In advance, I am immensely grateful and, thank you very much for this great chance to learn and get to know this perfect tool that is Java ❤️❤️🥹

Since it seems that we already have an article about using Java in VSC and at an article about IntelliJ is in the process of being added in #62, I think another article should be added for the Eclipse IDE.

There are many people using it so it would be weird to leave it out.

Website section

Learn > Tutorials > Your First Java App

Details

I could imagine the following sections:

• Introduction/installation
• creating Java projects
  • possibly including build tools (I am not talking about an introduction to build tools, just about creating Maven/Gradle projects in Eclipse)
• Debugging functionality (Debug perspective, associated buttons, etc)
• Content assist
  • I don't think it's necessary to talk about setting auto activation keys but this is a possibility as well.
• Differentiation between workspaces and projects
• possibly Ctrl+1 (quick fix), Ctrl+3 (quick access)
• Refactoring/Generation/Autoformatting
  • only a quick overview showing the options being there
  • not including any configuration of autoformatting etc

Author references

I would be interested in writing this but I am also open to other people writing it.

Approved Content Discussed in #22

See JEP 321.

On /learn, the section References for the latest release contains multiple links to sites about JDK 21 even though the latest release is 22:

• Java Documentation
• Java API Docs
• Java Release Notes

I propose to either update these links to 22 or change the heading to not say "latest release".

Approved content Discussed in #21

The heading of the article about jmap is

Jmap - Printing Detais of a Process

It should be Details instead of Detais.

The said article is not a part of this repository.

What is concurrent programming? Why do we do it? How do we do it safely? On the latter question, there's lots to explore:

• thread pools vs virtual threads (what to use when?)
• concurrent data structured (see #9)
• locks, semaphores, etc.

Basically, everything in a java.util.concurrent.* package.

Request Issue

No response

Website Section

Learn > Tutorials > Mastering the API

Proposal Details

It would be very interesting if content related to JDBC/JPA and also about Networks were added to the "mastering the api" section.

Author References

No response

When viewing the article I wrote on enums, it sais

Last update: Invalid DateTime

at the bottom.

However, this timestamp is displayed correctly when I locally run the version of the site in this repository:

Last update: September 29, 2023

The Serialization section on the records article contains the following sentence:

Deserializing a record always call the canonical constructor.

I think this should be either

Deserializing a record always calls the canonical constructor.

or

Deserializing a record will always call the canonical constructor.