This looks good Stuart. -Chris.
On 10 Dec 2015, at 00:22, Stuart Marks <stuart.ma...@oracle.com> wrote: > Hi all, > > > Joe Darcy pointed out that API changes I pushed into jdk9-dev yesterday are > missing wildcards from the Map.ofEntries() method. Please see this bug: > > https://bugs.openjdk.java.net/browse/JDK-8144952 > > The Map.ofEntries() method currently has the following declaration: > > static <K, V> Map<K, V> ofEntries(Entry<K, V>... entries) > > it should be changed to > > static <K, V> Map<K, V> ofEntries(Entry<? extends K, ? extends V>... entries) > > This doesn't make all that much difference in practice. For example, this > works: > > Map<Number, Number> map1 = MapOfEntries(entry(1, 2.0), entry(3.0f, 4L)); > > However, this does not: > > Map.Entry<Integer,Double> e1 = Map.entry(1, 2.0); > Map.Entry<Float,Long> e2 = Map.entry(3.0f, 4L); > Map<Number,Number> map = Map.ofEntries(e1, e2); > > After adding the wildcards, the latter example compiles fine. This is a > pretty unusual case, but for maximum flexibility it's probably a good idea to > add the wildcards anyway. > > Please review the diff appended below. > > Thanks, > > s'marks > > # HG changeset patch > # User smarks > # Date 1449706837 28800 > # Wed Dec 09 16:20:37 2015 -0800 > # Node ID b6540a8b7ab064600fe49a8bc678ad96127090ca > # Parent 7f644a5d554a67457f3dd535c4435643d3f65569 > 8144952: add wildcards to the Map.ofEntries() method > Reviewed-by: XXX > > diff -r 7f644a5d554a -r b6540a8b7ab0 > src/java.base/share/classes/java/util/Map.java > --- a/src/java.base/share/classes/java/util/Map.java Wed Dec 09 15:27:21 > 2015 -0500 > +++ b/src/java.base/share/classes/java/util/Map.java Wed Dec 09 16:20:37 > 2015 -0800 > @@ -1670,9 +1670,9 @@ > */ > @SafeVarargs > @SuppressWarnings("varargs") > - static <K, V> Map<K, V> ofEntries(Entry<K, V>... entries) { > + static <K, V> Map<K, V> ofEntries(Entry<? extends K, ? extends V>... > entries) { > Map<K, V> map = new HashMap<>(entries.length * 4 / 3 + 1); // throws > NPE if entries is null > - for (Entry<K, V> e : entries) { > + for (Entry<? extends K, ? extends V> e : entries) { > // next line throws NPE if e is null > map.put(Objects.requireNonNull(e.getKey()), > Objects.requireNonNull(e.getValue())); > } > diff -r 7f644a5d554a -r b6540a8b7ab0 test/java/util/Map/MapFactories.java > --- a/test/java/util/Map/MapFactories.java Wed Dec 09 15:27:21 2015 -0500 > +++ b/test/java/util/Map/MapFactories.java Wed Dec 09 16:20:37 2015 -0800 > @@ -377,4 +377,13 @@ > assertEquals(sie.toString(), kvh1.toString()); > } > > + // compile-time test of wildcards > + @Test > + public void entryWildcardTests() { > + Map.Entry<Integer,Double> e1 = Map.entry(1, 2.0); > + Map.Entry<Float,Long> e2 = Map.entry(3.0f, 4L); > + Map<Number,Number> map = Map.ofEntries(e1, e2); > + assertEquals(map.size(), 2); > + } > + > }
