Hi Ivan,
On 15/08/18 1:20 PM, Ivan Gerasimov wrote: > Hi Jaikiran! > > The first part (the documentation clarification) was requested some > time ago [1], so it may be eventually fixed. > > [1] https://bugs.openjdk.java.net/browse/JDK-7033681 Thank you for pointing to that one. I hadn't found it during my search before sending this mail. > > With respect to the second part (throwing UOE from remove(Object)), I > agree with you that it would be more consistent to always throw it, > regardless of the presence of the searched item. > However, it would introduce a change of behavior, so I think it's > unlikely to happen. I understand. > > It may make sense to update the documentation for all the > structurally-modifying methods of Collection/List (remove(Object), > retainAll, removeAll, clear) in the same way it was done for > List.removeIf() here [2]. > > [2] https://bugs.openjdk.java.net/browse/JDK-8023339 I looked at that commit and yes, a similar @throws explaining the UnsupportedOperationException will be helpful. -Jai > > With kind regards, > Ivan > > > On 8/14/18 10:58 PM, Jaikiran Pai wrote: >> Consider the following code: >> >> import java.util.Arrays; >> import java.util.List; >> >> public class ArraysAsListTest { >> >> public static void main(final String[] args) throws Exception { >> final List<String> someList = Arrays.asList(new String[] >> {"a"}); >> System.out.println("Removed? " + someList.remove("a")); >> } >> } >> >> It uses Arrays.asList to create a java.util.List and then calls a >> list.remove(...) on it. This currently runs intothe following exception: >> >> Exception in thread "main" java.lang.UnsupportedOperationException: >> remove >> at java.base/java.util.Iterator.remove(Iterator.java:102) >> at >> java.base/java.util.AbstractCollection.remove(AbstractCollection.java:299) >> >> at ArraysAsListTest.main(ArraysAsListTest.java:8) >> >> The javadoc of Arrays.asList[1] states the following: >> >> "Returns a fixed-size list backed by the specified array. (Changes to >> the returned list "write through" to the array.)..." >> >> and has no other mention of how it's supposed to behave with "write" >> operations. Given that the javadoc states that the returned list is >> "write through", would that mean a "add/removal" is allowed? Probably >> not, because it does say it's a fixed size list.So the size altering, >> write operations (like add(), remove()) aren't allowed, but that isn't >> clear from the javadoc. So should the javadoc be updated to clarify the >> semantics of what changes are "write through" and what changes are not >> supported? >> >> Furthermore, the UnsupportedOperationException isn't always thrown from >> such a returned list. Consider this minor modification to the above >> code: >> >> final List<String> someList = Arrays.asList(new String[] >> {"a"}); >> System.out.println("Removed? " + someList.remove("b")); >> >> I add "a" and remove "b". This now runs fine without exceptions and >> prints "Removed? false". Should the implementation just throw the >> UnsupportedOperationException irrespective of whether or not the element >> is contained insuch a returned list? If not, should that be made clear >> in the javadoc (maybe same for addoperations)? >> >> [1] >> https://docs.oracle.com/javase/10/docs/api/java/util/Arrays.html#asList(T...) >> >> >> -Jaikiran >> >> >> >
