- Java 21 Virtual Threads
A virtual thread is a thread that costs almost nothing to create. You can have millions of them. That single change removes the reason most server code was written asynchronously, and it is the biggest thing to happen to Java concurrency in twenty years. The problem A platform thread — the only…
- Greedy Algorithms
Take the best-looking option at each step and never reconsider. Fast, simple, and correct only when the greedy choice property holds — with a worked case where greedy returns three coins and dynamic programming returns two, so you can see it fail.
- Spring Boot – Stateless API Authentication with JWT
Issuing a token at login, validating it in a OncePerRequestFilter, and putting the result in the SecurityContext. Where the signing key comes from, what does and does not belong in a claim, and the honest trade-off nobody mentions: a stateless token cannot be revoked.
- Python – Class
Writing a class: `__init__`, what `self` actually is, instance versus class attributes, methods, and `__repr__` — the dunder that pays for itself the first time you print a list of your objects.
- Java 17 Migration Guide (11→17)
Moving from Java 11 to 17 is a much smaller job than 8 to 11. Nothing large was removed from the JDK. The one change that breaks builds is strong encapsulation — reflective access into JDK internals stopped being a warning and became an error. The change that matters Java 9 hid the JDK's internal…