Andrew Geery created WICKET-5846:
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Summary: Widen generic definition on AbstractRangeValidator
Key: WICKET-5846
URL: https://issues.apache.org/jira/browse/WICKET-5846
Project: Wicket
Issue Type: Improvement
Components: wicket
Affects Versions: 7.0.0-M5
Reporter: Andrew Geery
Priority: Minor
I ran into a problem extending
{{org.apache.wicket.validation.validator.AbstractRangeValidator}} to work with
{{java.time.LocalDate}} in Java 8.
The problem is the generic R parameter in {{AbstractRangeValidator}}:
{code:java}
public abstract class AbstractRangeValidator<R extends Comparable<R> &
Serializable, V extends Serializable> { ... }
{code}
The issue is that while {{LocalDate}} is both {{Serializable}} and
{{Comparable}}, it doesn't implement {{Comparable<LocalDate>}}, as required by
{{AbstractRangeValidator}}. Instead, it implements
{{Comparable<ChronoLocalDate>}}.
In order to get {{AbstractRangeValidator}} to work with {{LocalDate}}, we need
to relax/widen the definition of R to extend Comparable that is bound to a
super of R:
{code:java}
public abstract class AbstractRangeValidator<R extends Comparable<? super R> &
Serializable, V extends Serializable>
{code}
As this definition is slightly wider than the previous definition, all previous
uses will continue to be valid. The advantage to making this change is that it
allows the {{AbstractRangeValidator}} to work with other classes like
{{LocalDate}}.
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