Bug: https://bugs.openjdk.java.net/browse/JDK-4497648
Webrev : http://cr.openjdk.java.net/~prr/4497648/
TextLayout is a final class that derives directly from Object.
It defines
boolean equals(TextLayout)
and over-rides
boolean equals(Object)
int hashCode();
The hashCode() delegates to the implementation class TextLine().
TextLine is also a final class that directly derives from Object
It does over-ride Object.hashCode() but *does not* over-ride
Object.equals(Object).
Aside from this breaking the rule that you should over-ride neither or
both -
migitated only by the fact that this is a non-API class -
the equals(..) methods on TextLayout() delegate to this class.
The result of all this is that TextLayout.equals(..) is really
Object.equals(),
whilst TextLayout.hashCode() is not Object.hashCode().
Further the javadoc on TextLayout.equals(TextLayout) says that the
compared instances are equal if they contain the same glyph vectors.
Note that whilst there is this and other commentary on the class
mentioning glyph vectors, the GlyphVector class is not exposed
anywhere in the API of TextLayout and we can take this only to
infer that it is implying that the laid out text is equivalent.
But as already noted there is no implementation to support
comparing the internal state.
Since this state of affairs goes back to 1.2 and it is neither easy,
nor obviously valuable to be able to make such comparisons, we
should make the spec. match the long standing implementation.
So this fix removes the over-rides that add no value, and removes
the wording about equal glyph vectors in favour of text that cannot
be used to interpret that there is anything other than the minimal
equivalence of equals. It would have been better if equals(TextLayout)
had not been added at all but that ship has sailed.
FYI .. I have already discussed this proposal off-line with the JCK team
and they are happy so long as the spec. matches the implementation.
CCC will be filed once this is reviewed - and I also had an off-line
conversation with Joe Darcy.
-phil.
