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What happened?

I was playing around with the Java Playground, choosing different examples from the list. For some of the examples, it worked fine in my mobile but when I tried again for the same examples it failed throwing an error - "Something went wrong. Please try again". However, the error was occurring erratically with no specific steps to reproduce.

However, I did not encounter this error in the desktop.

Mobile Details
Redmi 9A
Android 10
Chrome

OS

Other

What browsers are you seeing the problem on?

Chrome

Contact Details (optional)

[email protected]

What happened?

In the following snippet:

Collection<String> numbers = List.of("one","two","three");
numbers.remove("two");

System.out.println(numbers);

An unsupported operation exception must be thrown.

Playground output:

JShell Version 21.0.1 output:

OS

Linux

What browsers are you seeing the problem on?

Chrome

Contact Details (optional)

[email protected]

Additional information

Leave blank

What happened?

I'd like to suggest that the playground display what version of Java is being run and if any preview features are enabled.

It was not immediately obvious that Java 21 was what was being used. I had to test whether things like list.reversed() worked. It would be much better if this were visible to the end user.

Here are two mockups of possible ways to show it.

It's also unclear whether any preview features are enabled. Having a way to show that would also be helpful.

OS

macOS

What browsers are you seeing the problem on?

Firefox

Contact Details (optional)

No response

What happened?

In the "And the constant feature included in all JDK releases: Predictability" section, paragraph two:

"Oracle will not offer long-term support for JDK 22; we will provide updates until September 2023 when it will be superseded by Oracle JDK 23."

Year 2023 is behind us :)

Article Link: https://inside.java/2024/03/19/the-arrival-of-java-22/

What OS are you seeing the problem on?

Other

What browsers are you seeing the problem on?

No response

Contact Details (optional)

No response

What happened?

The following source code

var foo = "😄";

results in the error "Something is wrong!? Please try again." However, trying again produces the same error.

For reference: this is valid Java. Using JShell, I can write:

jshell> var foo = "😄"
foo ==> "😄"

Related is that using an emoji anywhere in code produces the "Something is wrong!?" error message, rather than a more specific error message that might better describe the real problem. Here are some examples of invalid code that have their issues masked by "Something is wrong!?":

var 😄 = "foo";

System.out.😄("Hello world!")

😄

OS

macOS

What browsers are you seeing the problem on?

Firefox

Contact Details (optional)

No response

What happened?

The title says it all: The default character encoding of the Dev.Java Playground’s console pane is US-ASCII. For maximum compatibility, it should be UTF-8.

Run:

System.out.println( System.out.charset() ) ;

US-ASCII

So of course characters in Unicode beyond ASCII are garbled.

Run:

System.out.println( "Kıvanç Aydoğan" ) ;

K?van? Aydo?an

Solution: Default the charset of the console pane to UTF-8.

OS

macOS

What browsers are you seeing the problem on?

Safari

Contact Details (optional)

[email protected]

Additional information

Leave blank

What happened?

The RSS feed on inside.java is broken again.

Specifically, there's an error on (currently) column 1 of line 199.

When viewing the content in an editor, I see a unicode special character there.

The article this is happening is JFR View Command - Sip of Java.
The last code block (containing Java Thread Statistics) has an invalid unicode character.

Steps to reproduce:

Go to https://inside.java/feed.xml
Observe that the XML content is not valid

What OS are you seeing the problem on?

Windows

What browsers are you seeing the problem on?

custom RSS reader, Firefox, Chrome

Contact Details (optional)

No response

What happened?

When viewing https://inside.java/2024/02/10/voxxxeddaycern-java-21-and-beyond/, I can see an escaped <iframe> tag missing the text iframe instead of the actual embedded content.

When curling the site, I see the following HTML:

<p>&lt;width=”760” height=”428” src=”https://www.youtube.com/embed/mWs6CXYbI6c” title=”YouTube video player” frameborder=”0” allow=”accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture” allowfullscreen&gt;&lt;/iframe&gt;</p>

The RSS feed is affected as well.

What OS are you seeing the problem on?

Windows

What browsers are you seeing the problem on?

Firefox, RSS reader

Contact Details (optional)

No response

What happened?

Thanks for the playground, it is quite handy.

I would like to request the ability to persist and generate URLs that link to user-created snippets.
This will make it possible to quickly prototype something and share it with one's colleagues or even on the internet.

The Golang playground offers this functionality e.g. https://go.dev/play/p/-MKUWeDBml7

OS

Other

What browsers are you seeing the problem on?

No response

Contact Details (optional)

No response

Additional information

No response

What happened?

Pasting following snippet in the Java Playground:

System.out.println("<p>test</p>");

Prints:

test

Instead of:

<p><test></p>

OS

Windows

What browsers are you seeing the problem on?

Chrome, Microsoft Edge

Additional information

Only tested Chrome and Edge

What happened?

When a line of the output is too long, the output dialog can go out of bounds with weird scrolling.

Example code:

System.out.println("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");

Output field:

when scrolling a bit to the right:

I would suggest to either add wrapping to the output field or allow horizontal scrolling inside it.

OS

Windows

What browsers are you seeing the problem on?

Firefox, Chrome

Contact Details (optional)

No response

Additional information

Leave blank

What happened?

When viewing the links on https://inside.java/, I can see

JEP targeted to JDK 22: 464: Scoped Values (Second Preview)

However, opening this redirects to JEP 463

Furthermore, JEP 464 (Scoped Values) is current Proposed To Target and not Targetted.

What OS are you seeing the problem on?

Windows, shouldn't matter

What browsers are you seeing the problem on?

Firefox, RSS feed

Contact Details (optional)

No response

What happened?

If you just put the character 😄 in a text prompt and hit Run, the Playground freezes.

For reference: doing this is JShell provides the following:

jshell> 😄
|  Error:
|  illegal character: '\ud83d\ude04'
|  😄
|  ^
|  Error:
|  reached end of file while parsing
|  😄
|    ^

OS

macOS

What browsers are you seeing the problem on?

Firefox

Contact Details (optional)

No response

Additional information

No response

For some time now blog posts containing links to JEP's and other articles redirect automatically.

Users should decide if they want to open the link after they read the short review.

This prevents Feedly from reading the short review as well.

Java Playground makes Java more accessible than ever by running in the browser and supporting code snippets and example templates. This is great for learning, experimenting, demonstrating, sharing - exactly what Java needs to attract and keep users and showcase Java in the best possible light.

However, much of what makes Java compelling is the platform and tools, not just the language. Showing Java via simple JavaScript tools can be self-defeating: it hides much of the platform, shows Java in a limited and less engaging way and implies that the best way to write Java is with another language.

Java Playground needs to add a basic set of 'standard modern IDE features' - and it needs to be implemented in Java itself, so this new site shows Java as powerful, flexible, exciting and makes it easy to write code. After all, modern tooling was invented in Java and it is much of what keeps developers excited.

I'm suggesting that dev.java consider changing the foundation of Java Playground to use SnapCode, a free in-browser code editor, written entirely in Java - running in the browser. It has these modern features already:

- Full code completion
- Support for balancing and highlighting paired chars (quotes, parens, brackets, etc.)
- Support for highlighting instances of selected symbols (variables, method names, etc.)
- Support for inline error reporting
- Support for in-browser UI coding (buttons, sliders, textfields, lists, tables, trees, etc.)
- Support for in-browser command line and chatbot processing (System.in / Scanner)
- Support for advanced charting (line, contour, 3D, etc.)
- Support for turtle/pen graphics, vector graphics and 3D programming in Java
- Support for quick access to documentation and library source
- Support for external library dependencies
- Support for UI building
- Support for debugging
- Support for graphics profiling (frame rate, painted region highlighting, etc.)
- Support for quick share of code snippets with encoded URL
- Support to show code as "Puzzle pieces" for visual drag-and-click code editing
- Ability to run on the desktop
- Much more!

Click to run SnapCode: https://reportmill.com/SnapCode/app/

I know the reaction might be "this is beyond our scope". But it's "Java Playground", not "Java Toy". Playgrounds are expansive, full-featured and inspiring - the limitation should be user imagination, not the tool. And I would love to help out.

Jeff at ReportMill

Contact Details (optional)

[email protected]

What happened?

The following statements

System.out.println("| " + Runtime.version());
System.out.printf("| %s%n", Runtime.version());

lead to

| 21+35-LTS-2513
java.io.PrintStream@314c508a| 21+35-LTS-2513

which contain an unexpected java.io.PrintStream@314c508a output (the value returned by System.out.toString()) start of the second one.

OS

Other

What browsers are you seeing the problem on?

No response

Contact Details (optional)

No response

Additional information

No response

What happened?

This might be a very tall order and out-of-scope of this playground,
but if the playground supports:

• surround it with docs (AsciiDoc or Markdown)
• support multiple snippets in one page on which one continue after the other
• import from Maven Central

it becomes as powerful Java alternative to Python's Jupyter notebook or Kotlin's notebook, making it much easier to teach the Java language to new students.

OS

Linux

What browsers are you seeing the problem on?

No response

Contact Details (optional)

No response

Additional information

Leave blank

What happened?

When viewing https://dev.java/community/, I see the following text in the Java 21 Launch section.

Java 21 is about to be released! Come celebrate it with us on the Java YouTube Channel on September 19th! From 13:00 to 21:00 UTC, we will be hosting an 8-hour live stream covering the launch of Java 21.

Since Java 21 has been released already, this information is outdated.

I am reporting this here since the devjava-content repository seems to not contain that part anyways.

What OS are you seeing the problem on?

Windows, shouldn't matter

What browsers are you seeing the problem on?

Firefox, Chrome, shouldn't matter

Contact Details (optional)

No response

What happened?

I have to move my hands from the keyboard, grab the mouse, and click the Run and Clear buttons.
Afterwards I have to click the text area to continue editing.

Consider adding a keyboard shortcut such as Control + Return for launching Run and showing the keyboard shortcut as a tooltip.
Consider moving the keyboard focus back to text area after launching Run and Clear.

OS

Windows

What browsers are you seeing the problem on?

Firefox

Contact Details (optional)

No response

Additional information

Leave blank

What happened?

It would be nice to have some examples of current Preview features such as JEP 430 String Templates.

OS

Windows

What browsers are you seeing the problem on?

Firefox

Contact Details (optional)

No response

Additional information

Leave blank