Community guides · Programming
How to write a comment that actually lands in r/java
r/java values acknowledged trade-offs. Replies that say 'this works at small scale but breaks at X' or 'this is fine in CPython but not PyPy' get upvoted.
What's hot in r/java now
What people are actually discussing
Top threads from the last month — what's getting engagement right now.
What this sub rewards
How replies earn upvotes here
- Senior-level technical depth is expected; avoid generic advice. Drop the 'try this' language. Show the code, the gotcha, and the production consideration.
- Concrete code or runnable examples are welcome where relevant. Snippets beat prose. Three lines with one comment beats a paragraph of explanation.
- Acknowledge limitations, trade-offs, or uncertainty when relevant. Name when your approach breaks — concurrency, scale, legacy version, OS-specific.
What good looks like
Real comments that landed in r/java
Two recent highly-upvoted replies. Notice what they have in common — concrete, no preamble, no self-promotion.
"JSP was (is) pretty good templating language, especially its extensibility with custom tags, as well as JSTL and third party tag libraries. The interoperability based on a stable specification was impressive. In Pre-AJAX era you could implement pretty complex UI - forms with validation, tables, page decorations fairly efficiently with them. Compare it to the current state - there's no…"
"then it seems no one complained ;)"
The one rule that gets posts removed
Skews toward professional developers — production-quality content expected.
Your pre-reply checklist
Before you hit Reply — four quick checks
Does my comment add something specific, not just an opinion?
A useful reply names a number, a method, a personal experience, or a concrete example. If you could replace your draft with "I agree" and lose nothing, rewrite.
Have I read the top 3 comments already on this thread?
If the highest-upvoted reply already says what you were about to say, your comment will sink. Add what's missing — counterexamples, edge cases, the next step — not what's there.
Would my reply still work if my username was removed?
If it only makes sense because it promotes you, your product, or your platform, this sub will spot it. Frame the value as "this solved it for me," not "check out my…"
Did I skim the sidebar rules one more time?
Every sub has at least one rule that surprises outsiders — peer-review only, no images, no specific tags, no off-topic. Five seconds in the sidebar can save you a removal.
Want to draft this reply with the rules already baked in?
Try Redimates — free, 10 replies / week