Can I please get a review of this change which proposes to fix
https://bugs.openjdk.org/browse/JDK-8292317?
The `java.util.Iterator` has a `forEachRemaining(Consumer<? super E> action)`
method. As per its contract, the implementations are expected to throw a
`NullPointerException` if the passed `action` is `null`.
`java.util.Collections` has a couple of places where it wraps the passed
`action` into another and passes that wrapped `action` to the underlying
`java.util.Iterator`'s default `forEachRemaining` implementation which is:
Objects.requireNonNull(action);
while (hasNext())
action.accept(next());
Since the passed `action` is now a non-null wrapper, the implementation goes
ahead and advances the iterator to the next entry and invokes on the non-null
`action` to carry out its action. That non-null wrapper action then calls the
`null` user passed action and runs into an expected `NullPointerException`.
However, at this point the iterator and already advanced and that is what the
bug is.
The commit in this PR introduces a trivial null check on the `action` very
early in the call even before wrapping such an `action`. This prevents any
further logic to execute if `action` is null.
New test methods have been added to the existing test class
`test/jdk/java/util/Collections/DelegatingIteratorForEachRemaining.java`. This
test class was introduced in https://bugs.openjdk.org/browse/JDK-8205184 where
this delegation logic was added for the `forEachRemaining` methods. These new
test methods reproduce the failure and verify the fix.
-------------
Commit messages:
- 8292317: Missing null check for Iterator.forEachRemaining implementations
Changes: https://git.openjdk.org/jdk/pull/11154/files
Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11154&range=00
Issue: https://bugs.openjdk.org/browse/JDK-8292317
Stats: 41 lines in 2 files changed: 40 ins; 0 del; 1 mod
Patch: https://git.openjdk.org/jdk/pull/11154.diff
Fetch: git fetch https://git.openjdk.org/jdk pull/11154/head:pull/11154
PR: https://git.openjdk.org/jdk/pull/11154
