It's not quite as easy as it seems, because these methods are "intrinsics". That is, the pure Java code you see is not always the one that gets used; instead, the JIT compiler can use a faster implementation that uses vectorized assembly or whatever. (That's why you see "@IntrinsicCandidate" on compress() and toBytes() in StringUTF16.java)

But I think your idea would also be possible to implement in vectorized assembly, so it still works!

The rule for most things (such as ArrayList) in the JDK is: "if you use race conditions to break this thing, that's your problem, not ours". But String is different: it's one of the few things meant to be "rock-solid, can't break it even if you try", so I think this bug in String would qualify as a potential security issue in their mind: there are many places in Java that trust Strings not to act weird, and some of them are even in native code deep in the guts of the VM.

On the other hand, String is used all over the place so having to introduce a performance regression to fix this bug would be quite painful. All of the other proposed solutions in this thread introduce an extra copy, and an extra pass over the string. Your fix is basically no extra cost, and as a bonus, can be tweaked so each char in the array is read only once.

Which means that the bug can now be fixed "guilt-free", if anyone from the JDK team is reading this thread. Though they have some pretty clever people there too, so they might have thought of it eventually for all I know.

Example: suppose I offer you free email hosting "forever". Should you believe me? What if I go out of business? Well, in that case, I can at least ensure that your email address gets transferred to a different provider, so I'll still have kept my promise. So maybe this particular promise is believable.

But that only works because email is more or less a standard so there are many providers. Suppose I offer something that no one else does. Can you trust my promise that it will be "free forever"? Clearly, if I go out of business, then no.

Can I at least make a conditional promise that it will be free "as long as I'm in business"? But suppose I'm a month from bankruptcy, and my accountant tells me that getting rid of my free tier would save me. Surely, it's better for my free users to lose service rather than ALL my users losing service. So, unless you're sure I'd never be in that situation, you shouldn't believe me when I say "as long as I'm business this will be free".

Okay, how about a vague promise like "this service will keep its free tier around unless the business is in a desperate situation of some kind"? That's a promise that I could indeed keep, if I decide it's important enough... unless... how sure are you that I'll remain in full control of what is currently "my" business? What if I take my company public? I might then be kicked out by the board. (It happened to Steve Jobs, right?) So either my "free forever" promise means I'm not allowed to go public, or at least I need to do some very careful legal acrobatics to ensure that the board can't go back on my promise, even if they kick me out.

Still, if you find yourself needing to break a promise you made about "forever" a mere month after you made it, you should probably at least apologize instead of just hoping that no one remembers that you ever made such a promise. Chances are, they will indeed remember. If "it's the right thing to do" is not enough motivation, then do it for the brownie points, you'll get more of them this way. ("Who cares about brownie points?" you ask? Well, clearly, if they weren't worried about brownie points then they wouldn't be playing this weird game of "let's pretend we never said the forever".)

And it further implies that these people don't immediately follow that thought with: "That's surely impossible, since it would be a privacy nightmare if literally everyone in the world could track everyone else in the world's every move".

Or perhaps with this alternative thought, which would lead to the same conclusion: "let's not worry about privacy, how would this even work? Does every phone company in the world pro-actively send every customer's location data to OpenCage, just in case someone queries it? Or does OpenCage wait until it gets a query, and only then query the cell phone company 'just-in-time'? Both of these sound like a lot of work for each phone company to support ... what's the incentive?"

Honestly, I'm a bit surprised that the OpenCage blog post is so calm about this, instead of just yelling incoherently "why WHY why would anyone think like this?!?"

https://www.tuhs.org/cgi-bin/utree.pl?file=V3/man/man2/time....

vs

https://www.tuhs.org/cgi-bin/utree.pl?file=V4/man/man2/time....

EDIT: note that back then, it was a signed integer. Turns out that people wanted to be able to represent dates from before 1970 so we lost one bit.

The article mentions Java's LinkedHashMap, which actually can do LRU. But as the name implies, they rely on a linked list, where move=to-front is natural.

But this superpower does not come for free: a Java-style linked hash map will use more memory than the technique described in the article.

1. MyClass has 10 private fields, each with a trivial getter and setter.

2. YourClass has 10 private fields, of which 9 have a trivial getter and setter. The last one has a trivial getter but the setter is non-trivial.

If you use your IDE to write your getters and setters, than the two classes above will look the same at glance.

If you use Lombok, the "special" field will stick out at once.

Personally, I prefer to avoid Lombok and just use public fields. That way, the field with a nontrivial setter will also stick out, and no need for bytecode magic.

In that case, the compiler could make a specialized qsort using intcmp automatically.