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https://issues.apache.org/jira/browse/PDFBOX-5724?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17792626#comment-17792626
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Axel Howind commented on PDFBOX-5724:
-------------------------------------
Yes, since both keywords are evens, the if-block can be simplified to
return that.type1Keyword == type1Keyword && that.type2Keyword ==
type2Keyword;
That would be a correct implementation according to Java contentions. I am just
reluctant because whoever wrote the code seemed to have something else on his
mind and I don’t know if there’s any reason buried in the pdf spec to consider
two instances equal maybe if one only has one of the keywords set. Anyway once
equals() is changed, we need to look at hashCode() too.
> CharStringCommand.equals() does not conform to the contract of Object.equals
> ----------------------------------------------------------------------------
>
> Key: PDFBOX-5724
> URL: https://issues.apache.org/jira/browse/PDFBOX-5724
> Project: PDFBox
> Issue Type: Bug
> Affects Versions: 4.0.0
> Reporter: Axel Howind
> Priority: Critical
>
> The equals() method in CharStringCommand breaks the contract of
> Object.equals(). From the Object.equals() Javadoc:
>
> {quote}The {{equals}} method implements an equivalence relation on non-null
> object references:
> * It is {_}reflexive{_}: for any non-null reference value {{{}x{}}},
> {{x.equals(x)}} should return {{{}true{}}}.
> * It is {_}symmetric{_}: for any non-null reference values {{x}} and
> {{{}y{}}}, {{x.equals(y)}} should return {{true}} if and only if
> {{y.equals(x)}} returns {{{}true{}}}.
> * It is {_}transitive{_}: for any non-null reference values {{{}x{}}},
> {{{}y{}}}, and {{{}z{}}}, if {{x.equals(y)}} returns {{true}} and
> {{y.equals(z)}} returns {{{}true{}}}, then {{x.equals(z)}} should return
> {{{}true{}}}.
> * It is {_}consistent{_}: for any non-null reference values {{x}} and
> {{{}y{}}}, multiple invocations of {{x.equals(y)}} consistently return
> {{true}} or consistently return {{{}false{}}}, provided no information used
> in {{equals}} comparisons on the objects is modified.
> * For any non-null reference value {{{}x{}}}, {{x.equals(null)}} should
> return {{{}false{}}}.{quote}
> This is the current implementation:
> {code:java}
> @Override
> public boolean equals(Object object)
> {
> if (object instanceof CharStringCommand)
> {
> CharStringCommand that = (CharStringCommand) object;
> if (type1KeyWord != null && type1KeyWord ==
> that.getType1KeyWord())
> {
> return true;
> }
> if (type2KeyWord != null && type2KeyWord ==
> that.getType2KeyWord())
> {
> return true;
> }
> if (type1KeyWord == null && type2KeyWord == null)
> {
> return true;
> }
> }
> return false;
> }
> {code}
> If type1Keyword==null and type2Keyword!=null, true is returned without
> checking the values of that.getType1Keyword() and that.getType2Keyword().
> Now imagine a has both fields set to null and b has not. Then
> a.equals(b)==true and b.equals(a)!=true.
>
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