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https://issues.apache.org/jira/browse/PDFBOX-5724?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17792658#comment-17792658
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Axel Howind commented on PDFBOX-5724:
-------------------------------------
OK, I'll try and run some tests and if nothing breaks, create a patch.
> 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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