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On Thu, Feb 9, 2017 at 5:32 PM, Jeff Dinkins <jeff.dink...@oracle.com> wrote: > > Adding Mike’s current email. > > -jeff > >> On Feb 9, 2017, at 10:18 AM, Volker Simonis <volker.simo...@gmail.com> wrote: >> >> Hi, >> >> I want to finally resolve this long standing issue (or close it as >> "will not fix" if that's not possible): >> >> http://cr.openjdk.java.net/~simonis/webrevs/2017/8033909/ >> >> This change has already been discussed in length on the mailing list: >> >> http://mail.openjdk.java.net/pipermail/core-libs-dev/2014-February/thread.html#24989 >> >> and in the bug comments: >> >> https://bugs.openjdk.java.net/browse/JDK-8033909 >> >> So I'll give just a short summary here: >> >> - Objects.requireNonNull(T, Supplier) does not check for the Supplier >> argument being null. Instead it relies on the fact, that the VM will >> implicitly throw a NullPointerException when it calls .get on the >> Supplier argument during the creation of the explicit >> NullPointerException which it is supposed to throw. >> >> - this behavior slightly differs from Objects.requireNonNull(T, >> String) which simply creates a NullPointerException with a null >> message in the case where the String argument is null. >> >> - the difference is not evident in the OpenJDK, because the HotSpot VM >> creates a NPE with a null message by default if we call a method on a >> null object. >> >> - however creating such a NPE with a null message when invoking a >> method on a null object is not enforced by the standard, and other >> implementations can do better :) For the following trivial program: >> >> public class NonNull { >> public static void main(String[] args) { >> Supplier<String> ss = null; >> Object o = Objects.requireNonNull(null, ss); >> } >> } >> >> the current OpenJDK implementation returns: >> >> Exception in thread "main" java.lang.NullPointerException >> at java.util.Objects.requireNonNull(Objects.java:290) >> at NonNull.main(NonNull.java:8) >> >> but the SAP JVM will print: >> >> Exception in thread "main" java.lang.NullPointerException: while >> trying to invoke the method java.util.function.Supplier.get() of a >> null object loaded from local variable 'messageSupplier' >> at java.util.Objects.requireNonNull(Objects.java:290) >> at NonNull.main(NonNull.java:8) >> >> which is at least confusing for a call to Objects.requireNonNul() with >> a null Supplier. We think the exception should be the same like the >> one we get when invoking Objects.requireNonNul() with a null String. >> >> - because of this difference (and because we like our extended >> Exception messages :) the JCK test for Objects.requireNonNul(T, >> Supplier) (i.e. >> api/java_util/Objects/index.html#RequireNonNullMessageSupplier) was >> removed from TCK 8 and is still commented out in TCK 9 >> (npe_checkingNullSupplier() in RequireNonNullMessageSupplier.java). >> >> I really think that the simplest and most natural fix for this problem >> is to simply check for a null Supplier argument and create the NPE >> with an explicit null message in that case (as outlined in the >> webrev). This: >> - makes the two requireNonNul() overloads for String and Supplier >> behave the same (which I think was the initial intention). >> - doesn't require documentation changes >> - makes it possible to write a simple and conforming TCK test >> >> If we can't agree on this quickly, I suggest to close the issue as >> "will-not-fix" and leave it untested by the TCK. >> >> Thank you and best regards, >> Volker >> >> PS: the 'XS' obviously only applies to the fix, not to this message :) >
