The example class does not define hashCode() either...
Gary
On 2024/09/26 12:23:00 "Gary D. Gregory" wrote:
>
>
> On 2024/09/26 09:49:50 Alex Tsvetkov wrote:
> > Hi.
> >
> > I found a bug in the implementation of the method `equals` of class `Pair`.
> >
> > Implementation must be symmetric. Current implementation is not.
> >
> > Her test showing the problem:
> >
> > ```
> >
> > @Test
> > void run() {
> > var pair = Pair.of("a", "b");
> > var entry = new Map.Entry<String, String>() {
> > public String getKey() { return "a"; }
> > public String getValue() { return "b"; }
> > public String setValue(String value) { return null; }
> > };
> > assertTrue(pair.equals(entry)); // true
> > assertTrue(entry.equals(pair)); // false
> > }
> > ```
>
> This bug is in the test: The class violates the Map.Entry contract for the
> equals() method, so it's completely broken.
>
> The Javadoc for Map.Entry #equals(Object) in Java 8:
>
> /**
> * Compares the specified object with this entry for equality.
> * Returns <tt>true</tt> if the given object is also a map entry and
> * the two entries represent the same mapping. More formally, two
> * entries <tt>e1</tt> and <tt>e2</tt> represent the same mapping
> * if<pre>
> * (e1.getKey()==null ?
> * e2.getKey()==null : e1.getKey().equals(e2.getKey()))
> &&
> * (e1.getValue()==null ?
> * e2.getValue()==null : e1.getValue().equals(e2.getValue()))
> * </pre>
> * This ensures that the <tt>equals</tt> method works properly across
> * different implementations of the <tt>Map.Entry</tt> interface.
> *
> * @param o object to be compared for equality with this map entry
> * @return <tt>true</tt> if the specified object is equal to this map
> * entry
> */
> boolean equals(Object o);
>
> Gary
>
> >
>
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