AutoClosable and lists/hashmaps

[ashen mesa]

Is AutoClosable.close() called when removing an item from a list? What about when the object is a key or a value in a HashMap?

[smoky plover]

<@&987246399047479336> please have a look, thanks.

[smoky plover]

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[nova crown]

wdym, List and Map don't implement AutoCloseable

[ashen mesa]

no, when the .remove() function is called does it call AutoClosable.close() before removing it from the list

for the object that is being removed

[nova crown]

on what ? the object inside the list ? why would it ?

[ashen mesa]

yes, the object that is being removed inside the list. it would do this since it's being removed and will not be used anymore

[nova crown]

how can the list know that ? only the code which added to the list can know such a thing

[ashen mesa]

the list would know that since... it's being removed? I don't understand

if you remove an object from a list you most likely don't want it

[nova crown]

how can the list know remove = the item will never be used again ?

[ashen mesa]

oh i see

so the answer is no

thank you

[nova crown]

also note two things

1. The code creating something that can be closed should be the one closing it, not the method the object is passed into, that's because of responsibilities : a piece of code should be responsible for what it did, and what it did only, not more, not less
2. Methods shouldn't have side effects or anything that is not included in the name of the method, and so, a remove() method should only remove, it should never modify the removed object
   @ashen mesa

[ashen mesa]

thanks for this info

[nova crown]

And by 1), I mean :

void a() {
  try(Scanner scanner = ...) {  // Creates scanner here
    b(scanner);
  }  // Auto close scanner here
}
void b(Scanner scanner) {
  // b hasn't created scanner, and so it should never close it !
  println(scanner.nextLine());
}

@ashen mesa

[ashen mesa]

I understand, thanks